What You Are Actually Signing Up For

"It always takes longer than you expect, even when you take into account Hofstadter's Law." — Douglas Hofstadter

Your kid has seen BattleBots, and now they want one, preferably by next month.

So you go looking, and what comes back is a forum thread from 2013 where everybody already knows each other, or a course that wants three hundred dollars before it'll tell you what the robot itself costs. Somewhere along the way you find out the event you were aiming for closed registration two weeks ago.

What you actually wanted to know was simple. How much money and how many evenings does this take, before anybody commits to anything? This piece is the answer, starting with the boring parts.

The classes, briefly

Robot fighting is organized by weight, and the weight class decides almost everything else about the experience.

Antweight is one pound, and it's where you start. The parts are small and cheap, the arena is a box you could carry, and the whole robot fits in a shoebox with room for spares. Things do get broken, but it's not scary.

Beetleweight is three pounds, and it's the usual next step. Three times the weight means a lot more energy, more expensive parts, and a bigger jump than the number makes it sound.

The classes keep going above that, and so do the budgets and the safety rules. You don't need to think about them yet.

There's a second split that matters more than weight for a first build. In the plastic class, your frame and weapon have to be 3D printed plastic. In the open class, you can use anything.

The plastic class exists so someone with a 3D printer and no machine shop can compete, and that's who this course is for. Module 2, The Decisions Before the Build, goes through the reasons in full.

What a competition day actually looks like

It's nothing like the TV show, and that's mostly good news.

You show up in the morning and find a table. That table is your pit, where you'll fix the robot between matches, and it's where you'll spend most of the day.

You check in, the robot gets weighed, and it goes through a safety inspection. There's no arguing with the scale or the inspection. Module 11 is all about passing it, because failing it means driving home without having competed at all.

Matches are short. Expect a few minutes at most, often less, and a lot of them are decided well before time runs out. A whole match can be over faster than it took you to get the robot out of its case.

Then you fix it and go again. Most events run double elimination, so one loss doesn't knock you out. The real event happens in the gaps between matches, and you'll spend them with a soldering iron in your hand while someone else's match runs across the room.

Realistically, a first event gets you two to four matches. That's the number to keep in your head: a whole Saturday, a lot of waiting, and a handful of minutes of actual driving.

Tell your kid that number before you sign up. It's the expectation most likely to be off, and it's much better to reset it now than at two in the afternoon on the day.

All that waiting isn't dead time, though, and it took us until our first event to see it. Once your own robot is fixed and charged, go walk the pits. Everyone is working out in the open, and an hour of looking around teaches you more than a week of reading.

What tools are on their tables? How do they keep track of screws and spare parts? Did they bring a second robot, or a set of spare parts already put together, so a broken piece is a quick swap instead of a rebuild? What are they doing in the ten minutes before they get called up? Most builders are happy to talk about it, too, as long as you don't catch them in the middle of a repair.

You might also have no idea who you're standing next to. At our first event, the builder at the next table started pointing people out across the room, and it turned out some of the best-ranked builders in the hobby were right there in our bracket. We'd had no clue. We were too busy fixing our own robot to go watch how they worked, and that's the thing we'd do differently next time.

The one idea we did bring home came from a table near ours. It was a silicone work mat, the kind sold for electronics repair. You can set a hot soldering iron down on it without burning anything, and it has little compartments for screws, some with a magnetic strip, so you can lay the parts out in order as you take the robot apart and put it back together.

We didn't have one. Our screws kept rolling off the table onto the floor, and every time it happened we were down on the ground hunting for something the size of a grain of rice, or digging through the bag for a spare, with the next match getting closer. A mat like that costs about as much as lunch, and it would have saved us more time than anything else we could have brought.

What it costs

Before the numbers, here's what you're actually buying, because the names on a parts website don't mean much until you know what each thing does.

An antweight is a printed plastic box. Inside it are two small geared motors that drive the wheels, one faster motor that spins the weapon, a battery about the size of a matchbox, a radio receiver, and two little circuit boards called speed controllers that turn the signal from the receiver into power for the motors. Every listing you'll read calls those boards ESCs.

Add a power switch the safety inspector can reach from outside, a few bearings and screws, and the plastic to print the shell, and that's the whole robot.

Prices are from 2026, starting from an empty workbench. Where a line shows a range, that's the spread across different parts that do the same job. Everything else is basic hardware that costs about the same wherever you buy it. Treat all of it as a rough sense of scale, not a shopping list.

The total splits into four buckets, and only one of them is the robot.

The robot itself.

The bench, bought once. None of this gets used up, and all of it carries over to every robot after this one.

That assumes you already own a temperature-controlled soldering iron and a scale that reads to the gram. If you don't, add fifty to sixty dollars, and buy both before your first solder joint rather than after.

Bulk stock lasts several builds. It's the bucket people forget about, and it's why first orders usually come in higher than expected.

Spares, which are what let you finish an event once something breaks.

Spare weapons and chassis plates are just more filament, which is already counted.

Add registration, usually twenty to thirty dollars, and gas.

That comes to about $500 for a first robot at a first event, starting from nothing. Barely a third of it is the robot. The rest is a workbench setup and a supply cupboard you won't have to buy again, plus spares.

So there are really two numbers, and the smaller one is the fairer one to judge by. The robot plus the bench comes to about $300, and that gets you a legal robot you can enter.

Bulk stock is the one bucket you can't really plan, because it's made of things you find out you need along the way. Don't try to buy it all in the first order. We did, and ended up with 750 M3 screws and fifty feet of wire we never used, for a robot that takes about forty screws. Buy the robot and the bench, start building, and order supplies as the build tells you what it needs.

A second robot is roughly $200, because it draws on everything you already have. That's the number that tells you whether this is a one-time project or a hobby. Module 5, The Parts That Outlive the Robot, sorts out which parts belong in which bucket, and it matters more than any single purchase.

Why there are ranges instead of part numbers

This class is one pound, checked on a scale, and every part in those tables is competing with every other part for the same 454 grams. A stronger weapon motor is weight that came out of the armor. A bigger battery is weight that came out of the weapon. Brass inserts, so the screw threads survive twenty rebuilds, cost a few grams. Titanium screws save a fraction of a gram each, forty times over.

That's really the whole game, and it's why there's no single right part. Two people can build for the same class from the same catalog and end up with different robots, because they made different trade-offs. When two robots in a bracket look alike, and they will, the match comes down to who made the better trades.

How to read a design and figure out what it needs is Module 6, Sourcing a Build That Has No Parts List. The robots we actually built, and what building them taught us, are in Two Robots, One Pound, since a part number only really means something next to the design that needed it.

Where the weeks actually go

This is the part people underestimate the most.

Printing takes hours per part, and the body of the robot is several parts. A full set is an overnight job, maybe two.

Tracking down parts takes longer than building. Most published designs give you the shapes to print and not much else. There's no parts list, no links, and often not even all the sizes. Turning "38mm wheels, roughly 10mm wide" into an actual order is slow going, and Module 6, Sourcing a Build That Has No Parts List, exists because of it. Expect this to eat most of your calendar.

Assembly is a few evenings. Wiring is the part that needs care, and it goes better as one long uninterrupted session than four squeezed-in ones.

Driving practice is time you have to schedule, because nothing forces you to do it. Module 12 makes the case that it's the most valuable time in the whole project, and it's usually the first thing to get skipped.

Registration closes before you're ready. The deadline lands weeks before the event, and if you miss it you're waiting for the next one. Find that date first and plan backward from it.

What you need to own

• A 3D printer, or reliable access to one. It doesn't need to be expensive, but it does need to finish a print without you watching it. A printer that quits halfway costs you the part and the evening, and you'll be printing a lot of parts.
• A soldering iron with temperature control.
• A scale that reads to the gram, because weight limits are enforced and guessing doesn't work.
• Basic hand tools, mostly hex drivers.
• Digital calipers. They're about twenty dollars, and you'll use them on nearly every part.
• Space. Somewhere a spinning weapon is allowed, and where a practice robot can bump into walls.

That's it. No machine shop, no CNC machine, no engineering degree.

Each of those has three or four options behind it and a couple of ways to go wrong. The Parts That Outlive the Robot goes through them, including the sixty dollars we wasted on soldering tips we didn't need.

What you get back for it

Everything above is the bill. What you get back is what decides whether the bill was expensive.

One build takes a kid through all of this:

• Motor selection and gear ratios
• Battery chemistry and discharge limits
• Soldering, and wiring a power bus
• Radio setup and failsafes
• Print orientation and layer adhesion
• Fastener sizing and thread engagement
• The beginnings of why a part breaks where it breaks, rather than somewhere else

Half of that list would be a semester-long class somewhere, and your kid won't run into it in that order.

A gear ratio means nothing until the robot is too slow and you're down on the floor with a stopwatch trying to work out why. School usually teaches the theory first and hopes a use for it shows up later. A build hands you the problem first, and you learn the theory that evening because you need it.

They'll do every one of those things badly the first time. Everybody hits the same walls in roughly the same order, so none of it is personal. What makes one build different from another is what you do when you get stuck, and there's almost never a single right answer.

That's usually where the kid beats you. An adult who gets stuck reaches for how it's supposed to be done. A ten-year-old doesn't know how it's supposed to be done, so they suggest something ridiculous, and often enough the ridiculous idea works faster. Knowing the basics is what makes that kind of idea useful instead of random, which is a good argument for teaching the basics and then getting out of the way.

Who this suits

Three questions to ask yourself before you go further.

Does your kid like fixing things more than winning? You'll spend about ten times as long repairing as fighting, so a kid who only wants the fighting will find the day long. A kid who likes taking things apart will have the best Saturday of their year.

Can your household handle a robot getting wrecked? Partly that's about money, since you've just seen the numbers and none of this is cheap. Mostly it's emotional. Something you spent six weeks on can be over in forty seconds, on camera, in front of people. That's part of what the hobby is, and it's worth talking about before it happens.

And do you expect to be involved? We couldn't find a minimum driver age in any of the rules, and Texas Robot Combat's contract only requires that the team captain be an adult and that anyone under eighteen sign with a parent. So a six-year-old can drive, but a six-year-old can't solder, and the younger the kid, the more of the building falls to you. How much, and which jobs fit which ages, is Module 3, Building It With Them, Not For Them, and it's worth reading before you decide.

If the answer to all three is yes, the rest of this course is the how.

Find an actual event

Robot Combat Events lists most US events and has a map view. Each event posts its classes, rules, fee and registration deadline there.

In Texas that usually means Texas Robot Combat. TRC runs Plastic Ants as its own class alongside Open Ants and Open Beetles, and the plastic class is the one this course is aimed at. Their events are at REV Robotics in Carrollton, registration goes through Robot Combat Events, and they publish their own four rules documents instead of only pointing to the standard SPARC rulebook.

They also run builders-only test-and-tune days. Going to one before your first real event is about the best thing you can do with a Saturday. There's no bracket and no pressure, just a room full of people who'll happily tell you what's wrong with your robot.

If you possibly can, go watch an event first. Small events are often free to get into. An hour in the pits answers more questions than this whole course, and all it costs you is the drive.

So about $300 gets a legal robot to its first event, about $500 once the bench is stocked and the spares are packed, and each robot after that runs around $200. Most of the weeks go to printing and hunting down parts, and the date that sets your schedule is the registration deadline.

Put this to work. Before you spend a dollar, do the two free things. Find your nearest event on Robot Combat Events and write its registration deadline somewhere you'll actually see it. Then read the section for your class in that event's own rules. It's about two pages, and it settles half your shopping list.

No purchase, no commitment, and about half an hour. You go from a parent wondering whether this is doable to one with a date to plan backward from, and that's a much easier problem to solve.

From here, The Decisions Before the Build covers the three choices that come before your first purchase.