How To Make A Combat Robot - Antweight 150g
Ever dreamed of battling robots like in Robot Wars? Now imagine those fights, but scaled down to fit in the palm of your hand.
Welcome to the world of UK Antweight combat robots! These 150g machines may be small, but they pack a punch in the arena. Their lightweight design makes them a great entry point for beginners, offering an exciting blend of engineering, electronics and 3D design without the high costs of larger combat robot weight classes.
Whether you're a student, hobbyist or just curious about robotics, building an Antweight combat robot is an affordable and accessible way to dive into the action while also learning about STEM subjects to boot.
This guide will take you step-by-step through the process of building your own Antweight combat robot using our in-house designed modular combat robot “Modulant”. You’ll learn about components, design considerations, assembly techniques and even battle strategies to help you dominate your first competition.
Let’s get started!
Contents:
What Is an Antweight Combat Robot?
Antweight combat robots are one of the smallest classes of fighting robots in the UK, typically weighing no more than 150g. Despite their tiny size, comparable to a chocolate bar, they are built for intense battles in small arenas. These battles usually last around two minutes, where competitors aim to disable or outmanoeuvre their opponents using a variety of weapons such as spinners, flippers, or pushers.
These competitions often take place at local meetups, school events and even at engineering hubs like Accu, where enthusiasts gather to showcase their designs.
The weight class is particularly popular in the UK due to its low barrier of entry. Unlike the heavier robots seen on the TV show Robot Wars, Antweight robots require a much lower budget to build and maintain, making them perfect for beginners.
Their small scale makes them accessible to students and hobbyists alike, with many components being 3D printed to keep costs down. Builders often use materials like PLA or TPU for the chassis and armour, with miniature motors and batteries selected for maximum efficiency within the weight limit.
Why Build an Antweight Combat Robot?
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Low-Cost & Beginner-Friendly: Components are affordable and the learning curve is manageable and fun.
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Safe (Relatively!): While still requiring caution, these robots pose far less risk than heavier combat bots.
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Great for Learning STEM: Building one teaches essential skills in mechanical design, electronics and even coding or 3D modeling.
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Competitive Fun: Despite their size, they can deliver powerful hits and strategic battle tactics, making competitions thrilling.
If you’re interested in robotics, engineering or just want to build something fun, an Antweight combat robot is a fantastic place to start.
Combat Robotics 101: What To Know Before You Design.
Before diving into the details of building your first Antweight robot, it's important to consider your overall design strategy.
Combat robotics follows a Rock-Paper-Scissors style of advantages and disadvantages, meaning that different types of robots have strengths and weaknesses against each other. This forces you to think critically about your design choices from the very beginning.
Rock, Paper, Scissors: The Three Main Robot Types
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Rock: Tough armour, capable of deflecting weapon hits and pushing other robots around. These robots focus on durability and control rather than offence.
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Paper: Precision-based designs that rely on tactical weapons and superior driving skills to outmaneuver opponents. These robots often use wedges, lifters or control mechanisms to disable opponents.
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Scissors: Robots with high-damage, big-hitting weapons but little defence. These bots sacrifice durability for the ability to deliver knockout blows.
So, do you want to be a Rock with tough armour? A Paper bot using tactics and control? Or a Scissors bot with a massive weapon and high hopes? Understanding this from the start will help you design an effective and competitive combat robot.
Next, we’ll break down the essential components needed to bring your robot to life.
Designing Your Robot: Tips & Tools.
Now that you’ve got a brief understanding of the basics, it’s time to get designing. For your first Antweight combat robot and the sake of this article, we’re going to use our modular Antweight combat robot chassis, Modulant.
Download Modulant 3D Files Here.
At this stage you’re blending creativity with practical constraints like weight, durability and functionality. Our modular chassis takes away much of the fiddly design tasks, allowing you to focus on the most fun part of building combat robots: the weapons, armour and wheels.
Get Sketching.
The first step to realising your Antweight combat robot dreams is to begin sketching down your ideas. Think side profiles, top down and try to take into account your core design choice of rock, paper, scissors.
A great tip here is to use the Modulant design sheet linked to the button below so you can try to accurately scale your sketches to the chassis. You’ll thank yourself later when it comes to implementing your designs into CAD or even cutting out the templates.
Design for Assembly.
Next, you’ll want to make considerations and plan how parts will be put together. Think about how you’ll mount them to the Modulant body, access screws, replace parts when they’re inevitably destroyed and wire up any additional electronics.
Weapon & Armour Integration.
Try to ensure your weapon or armour is both effective and reliable. A powerful spinner might look cool but could damage your own robot if not properly balanced. Likewise, if your armour isn’t securely mounted, a spinning weapon could rip it straight off, leaving you a sitting duck. Don’t forget that you need to design a way to immobilise any spinning weapons for safety between rounds!
Low-Fidelity Prototyping.
Once you’ve got a good idea about what you want to create, the best thing to do is a low-fi prototype. We’d recommend 3D printing the Modulant chassis first, then start attaching cardboard cutouts of your armour and weapons to get a feel of how the finished model will look and operate.
Weight Management.
Remember, 150g isn’t much. Design with the weight of your robot in mind and prioritise essential features first. Your chassis, drive and control are paramount; only then focus on adding extras like armour or weapons. The Modulant chassis takes away some of this guesswork with a chassis weight including transmitter, battery motors and wheels of just under 95g using recommended parts, giving you another 55g to play with.
CAD Software.
When it comes to designing your Antweight combat robot, CAD software is a game-changer.
Free programs such as OnShape make it possible to 3D model every component of your build before hitting print. You can spot potential weak points, test weight distribution and confirm dimensions, all without wasting material. By taking the time to virtually prototype, you’ll save yourself a lot of trial and error in the real world. Plus, once your CAD files are ready, you can easily tweak and iterate on your design for future upgrades or repairs.
It’s worth mentioning here that learning CAD is an invaluable skill that will help any budding engineer get a leg up within the engineering industry.
Print Orientation & Material Choice.
While designing in CAD, considerations must be made to take into account which way up your design will 3D print. The ideal scenario is to print things with a flat base and no overhangs, but that isn’t always the case.
It’s worth mentioning that print orientation also plays a role in your part’s overall strength and durability; layer lines can be a weak point if they’re positioned incorrectly, which isn’t what you want when you're aiming for a durable combat robot.
Materials also play a big role:
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PLA: Rigid and easy to print but can be brittle under heavy impact.
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TPU: Flexible and shock-absorbent, ideal for bumpers or armour that take constant hits. It can be too floppy for prints that need rigidity.
Balancing stiffness and flexibility is key to a robust Antweight design. Think carefully about which parts need maximum rigidity, like chassis mounts and which ones could benefit from a bit of give, like protective panels.
Next, we will discuss some of the core components of an Antweight combat robot.
Essential Components of a Combat Robot.
Now that we’ve covered the design stage, it’s time to talk about the components and electronics you’ll need to build your antweight robot. It’s worth noting that both the design stage and component choice are harmonious, meaning that as you’re designing, you need to make allowances for the components you need to fit inside or on your chassis.
Chassis
Your chassis is your robot's backbone. Often 3D printed from PLA or TPU, it houses all of your other components and holds everything together. Our modular chassis offers a fine balance between lightweight and strength, giving you the freedom to attach almost anything to it, hence the name “Modulant”.
Drive Motors.
Drive motors are used to provide the power your robot needs to turn your wheels and move around the arena. They are your main source of movement and are needed in 95% of all robot builds. “N10” or similar micro gearbox motors are common choices, paired with grippy wheels for manoeuvrability. Best of all, the Modulant chassis is designed for these motors to drop straight in.
Wheels.
Just like your drive motors, the wheels on your robot are a crucial choice. Small and nimble or big and chunky, the choice is up to you. Each choice will have an impact on how well your robot can drive. Wheels with less contact area, by convention, offer less grip and traction, but are small enough to keep your robot slimline and responsive to drive.
Wheels with greater contact area offer more grip, which might make driving around or over other robots easier, and some even have armour benefits, but they’re heavier and can make your bot harder to control.
You can also think about the materials your wheels are made of, rubber, silicone, foam, TPU or anything else you can think of which is circular and provides grip.
Battery
Lithium polymer (LiPo) batteries are widely used due to their high energy density. A 2S (7.4V) battery is typical for Antweights as it delivers the voltage needed to power the receiver, which then powers all of your other electronics. The capacity is usually around 200mAh, which offers plenty of power for multiple fights before needing to recharge, but also is small and lightweight enough to fit inside your chassis. Don’t forget to store them in a Lipo bag for safety.
Receiver & Transmitter
The combo of a receiver and transmitter allows you to control your robot wirelessly. A common choice is a FLYSKY FS-I6 6-channel 2.4GHz transmitter paired with a small specialist Antweight receiver board known as a Malenki. This board handles the connection, programming and control of your drive and weapons with a tiny footprint.
Wiring & On/Off Switch.
The wiring between motors, batteries and your receiver is what allows everything to talk with each other. Most of this wiring is just positive and negative leads, but depending on weapon type, there might be additional channels to wire into. Crucially, don’t forget the inline on/off switch; this is what isolates power from your robot, allowing it to remain safe when turned off.
Select Your Components.
With your primary parts selected is time to work out how you're going to fasten this all together.
Modulant is great for this as it solves the work for you, In this build we have used the following:
For the primary Chassis and Panel Covers, these screws offer fantastic self threading in plastics like PLA:
2.5mm x 6mm Polyfix 30° Screws
For the front scoop to offer a flush finish. Ideal where you want your components to really secure parts without providing vulnerable targets to spinner weapons:
Once you’ve got the above components mapped out, that should lead to a moving Antweight robot. That said, all you’ve got right now is a moving chassis. The next step is to think about armour & wedges.
Armour & Wedges.
Armour is pretty self-explanatory; these can be panels made out of lightweight materials like polycarbonate sheets, offering impact resistance without pushing your bot over the weight limit. The key here is to have them swappable, so that if they get damaged, which they probably will, you can swap them out between fights without having to rewire anything.
Wedges are a bit more tactical, think of them as a piece of armour placed on the front of your bot with the main goal to act as a pusher. You want to try and get underneath your opponent (known as ground game), as this limits their manoeuvrability while allowing you to push them around the arena and hopefully into the pit.
Don’t worry about having to 3d print these parts. They can be simply cut out of raw material with a mini hacksaw and attached to the Modulant body with Polyfix Screws. Modulant does have some pre-made parts for it, which you can use and print, but half of the fun is coming up with your own inventions.
Weapon Mechanism & Extra Electronics.
Not every robot needs one, but additional weapons can include spinning disks that use ultra-fast motors to chip away and demolish your opponent, or by using a servo module, lifters or flippers to toss them into the air, out of the arena or into the pit.
These additional weapons and electronics can be powered by your Malenki receiver, but the separate motors or servos may require additional wiring and extra components than shown here. We’d recommend that your first bot focus on using Modulant with a wedge and some armour panels. Once you’re comfortable, start thinking about extra weapons, but don’t forget about the weight limit too.
Assembling Your Antweight Combat Robot.
With your components sourced and your first design finalised, it’s time to build. The assembly process requires care, but it’s where your concept finally comes to life.
Step-by-Step Assembly:
1) 3D Print Parts.
While not an assembly step, the first step to building your Antweight bot is to 3d print all the parts you want to use. Chassis and lid are essential, you can print your wedges and armour while assembling the core parts.
2) Inspect Electronics.
While things are printing, double-check you’ve got all the right electronic parts you need. Don’t forget about solder, insulation tape and additional wiring you might need. Get them all to hand at your workstation.
3) Prepare Your Chassis.
Clean up any 3d prints, file down any holes if necessary and check fit for all components. This means check things like your motors fit in place snugly and the lid mounting holes all line up.
4) Mount the Motors.
Use mounting brackets and the spaces provided in the Modulant chassis to secure the motors and gearboxes in place.
5) Install the Wheels.
Ensure wheels are firmly attached by pressing them onto the motor axles. You can then check that they spin smoothly. You will have motor resistance here, but they should still rotate without any clunks or jams. If they feel loose, it’s a good idea to superglue the wheels to the motor axles. Additionally, you can superglue the tyres onto the wheels too.
6) Place the Battery and Receiver.
Dry fit your electronic components, such as the receiver and battery, first without any glues or tapes, ensuring everything is snug and will fit correctly without awkward cable runs.
7) Connect the Electronics.
Probably the hardest but most fun part, wire and solder everything together. If you’ve never soldered before, we recommend reading up on this first, as there are certain safety precautions to take along with making sure your joints are secure enough to handle battle. You don’t want your joints to fail mid-fight.
A) First, wire the motors to the receiver.
The motors will need to be wired up to the two pads marked as “L” and “R”. “L” being the left motor and “R” being the right motor. It might be easier to solder on the leads to your motors first, while they’re not in the chassis, then install them and wire them to the correct pads. At this phase, wire the positive leads to the top row and the negative leads to the bottom row.
B) Second, wire your off switch.
Next, make sure you have your on/off switch wired in line on the positive lead of your battery connector.
C) Lastly, wire your battery wires to the Malenki.
Now, wire the loose ends of your negative battery connector and positive lead from your switch to the positive and negative pads on the Malenki. These are marked with “–” and “+” with “PRW” in between.
8) Fit Armour Panels.
Attach additional TPU or polycarbonate parts for protection, such as your wedge and armour panels.
9) Final Checks.
Now that you’ve assembled your electronics and chassis, do a final visual inspection of your wiring. Make sure everything looks good before even thinking about attaching a battery.
Testing, Troubleshooting & Tuning.
Safety First.
Assembly and power checks are two very different processes. Before attaching a battery, you need to be in a safe environment. The best place to test a robot is inside a combat arena, as it is designed from the ground up to withstand anything an Antweight robot can throw at it.
We appreciate that everyone might not have their own arena, so to minimise risk, perform drive and connection tests with any additional weapons disconnected. Even Antweight spinning weapons have the capability to cause damage and severe injury. If you need to test any spinning weapons, you must use either an appropriate safety box or test them in your local arena only.
Fail Safe.
In our example, we don’t have any weapons, but you should still treat your combat robot as dangerous, as it’s instilling good habits. A necessary feature for a robot with a weapon is the ability to “fail safe”. This means that if the connection from the transmitter is disrupted, e.g. the transmitter is turned off or there is a signal failure, then the robot returns to a safe state to be handled.
For spinning weapons, this is a still position; for flippers or crushers, this may be at the bottom or top of the weapon's travel, depending on its layout.
The drive for the robot must also be fail safe, as a robot that goes out of control is dangerous, and if a connection cannot be reestablished the only safe option is to let it run in the arena until the battery fails.
We recommend testing your drive and connection in a safe environment, with the robot secured using a cradle which elevates the wheels or a clamp, to ensure that the connection can be tested without the risk of the robot driving away.
Power On Procedure.
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Safety Bar On: Before thinking about powering on, the very first step is to make sure that any weapons are locked in place with a safety bar and any sharp items are sheathed with a protective cover.
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Connect Battery, DO NOT TURN ON: At this stage, only connect your battery and attach your lid. Do not turn your bot on yet. If your bot turns on once you connect the battery, immediately turn it off and make sure your on/off switch is correctly labelled for future safety.
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Transmitter On: Next, turn on your transmitter to make sure that once your bot has power, it has something to connect to.
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Transmitter Down: Once you’ve confirmed that your transmitter has powered up, place it down securely, making sure all of the controls are set to their zero positions. Do not pick it up again until your bot is in the arena safely.
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Place in Arena: Now it’s time to place your robot in the arena and turn it on. Once it begins powering on, immediately close any arena doors or safety box lids. Perform a safety check to make sure the area is now fully enclosed. If your robot has any mandatory safety bars for spinning weapons, remove them at this point, but only once your bot has powered up and connected to your transmitter to avoid any unwanted or unsafe movement.
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Pick Up Transmitter: Only now is it safe to pick up your transmitter and move onto the pre-battle checks.
Pre-Battle Checks.
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Driving Test and Motor Function: Ensure each wheel responds correctly to transmitter input. Does your bot drive forward when you press forward? Does it turn in the correct direction? If not, the polarity on one or both of your motors could be off.
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Weapon Test: If in a safe environment such as an arena, you can try to activate your weapon to observe speed, balance and reliability.
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Range of Motion: If you have a lifter or grabber powered by a servo, try and test the range of motion you have. Make sure to check it doesn’t collide with any wiring or body panels.
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Fail Safe: While we’ve already mentioned this, test it again in the proper environment. Does the failsafe activate upon powering down your controller?
Troubleshooting Tips.
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Robot Not Turning On? If your robot isn’t turning on, first check that your on/off switch is fully engaged. Next, check your battery connection to ensure the connector is correctly inserted. After, check your battery charge level. If after these, it’s still not turning on, chances are you’ll want to double-check all of your solder joints to make sure they’re making good contact and aren’t bridging across joints. If there are no power indicator LEDs on your receiver, it may be worth adding one into the circuit to ensure you can see if power is getting there.
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Robot Turning On But Not Moving? If your robot is turning on but not moving, check that it’s correctly connected to your transmitter. If this is your first time turning on, it can take a while for your receiver to correctly bind to the transmitter.
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Robot Turning On But Weapon Won't Spin? If your robot is turning on and driving, but your weapon won’t activate, check the connections between your receiver and weapon. If all the wires are connected, turn on the robot, give the drive stick a wiggle and listen for any beeps. If you have a brushless motor setup as your weapon, it should make a power beep when turned on and an arming beep when the transmitter is connected. If this doesn't happen, there may be an issue with your motor or ESC. A common fault is using over-length screws to fasten motors to a body. The screws end up too far into the winding causing damage.
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Reverse or Uneven Driving? Most commonly, this is due to the polarity of one or both of your motor connections. Visually monitor which way your wheels spin when pushing forward. Identify the motor/s which are heading in the wrong direction and switch the wiring around on the motor terminals to change the way they drive.
This can also be easily changed on most transmitters, to save time and soldering. -
Jerky Controls? If your bot drives unevenly or sporadically, you can try to adjust the endpoints and expo settings in your transmitter to adjust the sensitivity to your liking. Some layouts of robot drivetrains are naturally more twitchy, and may need more tuning or simply practice to tame the turning speed.
Fine-Tuning for Performance.
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Weight Distribution: If your robot handles top heavy, flipping over upon acceleration you might need to think about rebalancing your weight distribution for better handling.
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Low Traction: If you have low traction and are wheelspinning, try to add friction to your wheels. This could be grippier tyres or giving your wheels more contact.
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Magnetic Downforce: Try adding magnets to improve grip if your arena has a metal floor. The downforce provided can help to give your wheels more traction.
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Test Drive: The best fine-tuning you can do after this point is getting used to how your bot drives. Repeatedly test and take notes on how your robot performs under pressure and a variety of positions. Can your bot drive upside down? What if you get flipped on any of the sides? Can you get out of being pinned against the arena walls etc.?
By this point you should have a combat ready Antweight robot. Next, let’s explore what to expect at your first competition.
Competing and Improving Your Robot.
By this point if you’ve been following along you should have a driving, functional Modulant Antweight combat robot, congrats. Now it’s time to battle. Let’s discuss what you need to know about competing with your combat robot and what to expect.
Before the Competition:
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Prep your Prints: Probably the most important step here is to prep spares of all your 3d printed components. These are the most likely things to be broken between fights. Bringing spares allows you to repair between fights.
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Know the Rules: It’s a good idea to review the event’s rule set carefully. Modulant has been designed to fit within current Antweight rulesets but every competition might have variations on interpreting size, weight limits, safety checks and match formats.
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Arrive promptly: Arriving early gives you the opportunity to prepare and get ready. You can scope out the battle arena, get an idea of opponents you might face and most importantly, be prepared to have your bot inspected and attend the safety briefing.
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Pack a Toolkit: Just like your spares, make sure to bring your tools, screwdrivers, sidecutters, chargers and extra batteries. Field repairs are often necessary so bring along anything you think you might need to repair your robot.
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Safety Equipment: Often an afterthought, but make sure you bring all of your safety equipment such as a lipo bag for your batteries to be stored in safely, locking bar if you have a moving weapon and sharp edge protection for any blades.
At the Event:
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Technical Inspection: Before creating the fight brackets, officials will check your robot for compliance. This is done in your heaviest configuration if you’re swapping out armour pieces. Marshalls may request your battery to be brought separately to avoid risks when weighing in.
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Match Strategy: Once the bracket is live, check who you’re fighting against first. Observe opponents and plan your approach. Use arena hazards and angles to your advantage. If you have different armour configurations, change them to match the type of robot you’ll be facing.
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Stay Flexible: Things rarely go to plan. Adapt between rounds, repair quickly and learn as you go.
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Have Fun: Remember why you’re here. This isn’t the Olympics, it’s about having fun. Don’t lose sight of that.
After the Battles:
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Review the Footage: Record your matches if possible. Replays can reveal strengths and flaws.
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Ask for Feedback: Other builders are a valuable resource. Share tips and exchange ideas.
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Plan Upgrades: Use your experience to tweak the design, improve durability or trial a new weapon setup.
Every battle—win or lose—is a step forward in your robot-building journey.
Wrapping Up: From Blueprint to Battle
Building and competing with an Antweight combat robot is more than just assembling screws and 3d prints, it’s a hands-on journey through mechanical design, CAD, electronics and strategic thinking. Whether you're a hobbyist, student or a curious beginner, this weight class offers a rewarding introduction to the world of combat robotics.
By understanding the core principles, designing with intent and preparing thoroughly for competition, you’ll not only create a functional robot but gain invaluable engineering skills along the way. The Modulant chassis is your springboard, now it’s time to see what you can make of it.
Key Takeaways:
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Start Small, Think Smart:
Antweight robots are accessible, affordable and ideal for developing technical skills. -
Design Drives Performance:
Strategic decisions in design affect durability, mobility and combat effectiveness. -
Prototyping Saves Time:
Low-fi builds and CAD modelling reduce trial-and-error and speed up iteration. -
Component Choice Matters:
Matching motors, wheels and power systems is crucial for control and efficiency. -
Safety is Non-Negotiable:
From testing to competition, follow strict safety protocols to protect yourself and others. -
Every Match is a Lesson:
Competitions offer valuable feedback, use it to evolve and enhance your design.
FAQs
Q: How much does it cost to build an Antweight combat robot?
A: Most beginner builds can be completed for around £50–£100, depending on materials and whether you already own a transmitter, 3D printer, soldering iron and associated tools. If you’re at college or high-school, chances are you’ll have an electronics lab or society that can help get you access to the tools you need.
Q: Do I need to know how to code?
A: Not at all. Most Antweights use simple RC systems that require no programming. More advanced bots may include Arduino or custom controllers but that’s overkill for just getting started. If you’re able to simply download 3d print files and print them, that’s the hard part done.
Q: Can I use 3D printed parts?
A: Yes. PLA and TPU are commonly used in Antweight builds. They're affordable, customisable and ideal for prototyping. Our modulant chassis has tons of different combinations that you can simply download and print. If you’re handy with CAD you can even design your own attachments.
Q: How long does it take to build an Antweight combat robot?
A: Building your own Antweight combat robot can take anywhere from a weekend to a few weeks, depending on your experience and access to tools or printers. Using our pre-made modular chassis drastically reduces design time so you can get into the action fast.
Q: Where can I compete with my Antweight robot?
A: Events are held across the UK, often hosted by local clubs, universities, or companies like Accu. Online communities and forums such as Bristol Bot Builders list upcoming competitions.
Q: What’s the best weapon for a beginner?
A: The best weapon design to begin with are wedge designs or simple lifters. They’re a good starting point because not only are they effective, but they’re much easier to control, less complex to build and most importantly easier to test in a safe environment.