One of the most commonly asked questions to newcomers in combat robotics is, “What does it cost to build a combat robot”? While I often keep meticulous notes of links to products and prices, I also very intentionally make a point not to consciously add those things up in my head or spreadsheet, out of fear that I let the weight of that number overcome my enjoyment of the few minutes at a time I’m actually competing.
While I will not fully answer the question here, I will attempt to give a unique look into what it cost me post-event to keep a 3lb and 12lb bot updated and ready for the next event. Both Bagheera and Bigheera fought in the February 2026 NHRL event, but the path forward for both could not look more different financially.
Bagheera will show a low end of things. It has no redesigns, has cheaper and easier to make parts, and is… much smaller. Bigheera continued to show some weaknesses, and is now undergoing its first major overhaul thanks in very large part to my teammate Mark. On top of seeing some pieces trashed and being replaced by redesigned ones, the parts at 12lb just tend to be more expensive, and a lot more has to be custom machined.
Bagheera (3lb):
My long running 3lb bot had its worst showing at NHRL to date, going 0-2, keeping me out of the main tournament for the first time in 14 tries, and a cherry on top was entering XP and losing to Gremlin, the eventual winner of that bracket. Both Gremlin and War!Hard? inflicted heavy damage on my bot.That said, the bot has done extremely well for me outside of NHRL and with the exception of a slightly bigger battery, I couldn’t have more confidence in running it back and trying again as I prepare for i3 in Detroit this April.
Let’s start talking about those batteries, sticking with the same brand, I’m upping my GNB 4s batteries to 930mah. I had considered a rework to 5s, but size was an issue, and War!Hard? aside, I’ve had relative success in winning tip speed battles.
$77: 3 shiny new batteries
Past that, we’re looking at a lot of restock. This will become a much bigger issue in Bigheera, but my general rule of thumb is having two copies of a robot and a spare of most parts. And I realize this increases costs substantially, but always gives me peace of mind when it comes to repairs and having what I need. Uprights and bottom plates took a lot of hits, resulting in:
$27 - 3 right uprights (⅜” UHMW)
$19 - 2 left uprights (⅜” UHMW)
$46 - 3 bottom plates (2mm CF)
I’ve had my drive motors in for a combined 40+ fights and they have kept on kicking. That said, this event finally got enough screws to strip out of one to warrant replacement. And the two aforementioned slugfests each cost me a hub motor, although I might look to Frankenstein them together with other old parts in the future. So a Repeat order was needed:
$150 - Hubmotors
$50 - Repeat Max Mk. II
$25 - AM32 ESC
Wheels have been incredibly hearty on Bagheera, partially due to being pretty well protected, and heavily because of the amazing work of Matt Lantry. That said, facing some heavy hitters in the last event finally did some damage. To get back up to my normal stock I needed:
$10 - 2 front wheels
$4 - 1 rear wheel
I placed a big SendCutSend order for Bigheera, and a tiny drop in that financial ocean was some new shiny sharp blades for Bagheera.
$26 - 3 new blades
And of course you have to replace armor, which was hit really hard at NHRL. Thankfully I can estimate I had to print a whole big spool of purple TPU, which is generally the cheapest part of this sport.
$20 - 1 role of Overture TPU
Results:
Total Cost of Parts: $454
Total Cost of Shipping: $28
Total Cost for Bagheera: $462
I’ll admit, given this was the low end half of this article, I was expecting this number to be a bit more forgiving. That being said, specifically for the Detroit event I feel I could have gone without the Repeat order and brought the number down $225 and been just fine. But the parts I got will undoubtedly continue to be part of the design going forward, so no harm in having some extras.
Bigheera (12lb):
Now onto the “fun” part. In talking about how we wanted to handle improving the bot, specifically the weapon system, we had to balance my wallet (using as much existing stock/design as possible), and making what we thought was the best decision. Mark won most of those battles towards the latter option. So while I kept my drive and a bulk of my frame intact, v2 of the bot will now have a completely new weapon system, including the uprights and crossframe that support it. Of course there are also some other bits and bobs needed, so let's get to it.
Much like Bagheera, Bigheera took some big hits to the wheels. Some were just cracked Nylon, but with such an important piece of a big bot, better safe than sorry. Thankfully the bearings for the front wheels could be switched over.
$10 - 2 front wheels
$20 - 3 rear wheels
Wheels are nothing without something to spin on. Thankfully the motors that power everything have stayed intact, and for the most part so have the amazing HiveDrive gear boxes that take all that power and reduce it to something usable. That said, the same 4 have been in use across two copies of the bot since the beginning, and finally some mounting holes began getting stripped or bent. To ensure that all is well, I had to grab some new ones.
$104 - 2 HiveDrive gear boxes
And like with Bagheera, I would need about 2 rolls of TPU, and am doing a new part with 1 roll of Super PLA+. A vast majority of this will go towards some new wheel guards that are the main piece of armor on the bot.
$60 - Filament
At this point I am singlehandedly raising the stock price of Innov8tive Designs. I’ve been buying weapon motors after every single competition Bigheera has been in. The last event saw me have 3 fights and fry 3 motors. The hope in this redesign is that this becomes a thing of the past, but for now…
$238 - 3 BadAss 2826 motors
Of course why stop at incredibly expensive motors when you can add some reinforced shafts with extra length and better attachment? I already had 2, needed 1, but hell, why not have a spare.
$60 - 2 Maximizer shafts
Motors are a big expense, but it’s imperative to fix the reason they keep breaking down. This takes me to my friends at Zintilon across the pond for some new important chassis pieces. As this shockingly high number comes back, I take a large part of the blame. I like to make sure I have extra pieces (because of course this revision will be the one I use forever), and I got talked into getting powder coating for the cool purple look (more of Mark haunting my wallet).
$273 - 4 new weapon hubs
$341 - 3 new left uprights
$341 - 3 new right uprights
$159 - 3 new crossframes
I use a lot of carbon fiber and UHMW in Bagheera and Bigheera. That said, what I had in that department was almost untouched in Bigheera this time around. But the new changes require some new pieces for the inside, so included that in my mainly Bagheera focused RSL order.
$14 - 6 internal sorter pieces, 2mm CF
Along with Robot Smashing League and Zintilon, the third major source of the cut components for the bot is unsurprisingly SendCutSend. From there I needed a mix of items for the rework, please a few extras of some other things to make config swaps go a little faster.
$39 - 3 new wedge plates
$3 - 4 new wheelsguard plates
$79 - 8 ears in 7075 aluminum
$68 - 4 tapped weapon clamps
$46 - 2 overhead config blades
$70 - 2 horizontal config blades
$81 - 4 vertical config blades
$31 - 4 weapon spacers for conversion to horizontal/overhead
As we near the end of this section of redesign fueled purchases we have the new shaft. Previously it was a big ass shoulder bolt from McMaster. Not cheap, but not exactly crazy either. Not the case anymore. The entire redesign centers around a shaft that will help keep the rails from bending inward, and thus we have a custom Misumi shaft, bought in bulk so I hopefully never have to purchase another.
$181 - 5 custom double end tapped Misumi shafts
And finally, nothing new, nay, nothing much at all happens without our friends at McMaster. Not going to bother to itemize it out, but a variety of new bearings, washers, and some other items were needed.
$140 - Totally not 5 boxes of Swedish Fish.
Results:
Total Cost of Parts: $1,997
Total Cost of Shipping: $102
Total Cost for Bigheera: $2,119
So this is where I truly must reckon with how much I hate this exercise. This is where I understand that every time a decision has to be made I shut off my brain and go with my heart. But I again must note that I am not the most reserved when it comes to spares, nor the most equipped when it comes to access to big specialty tools. College teams and those with the proper stuff could have done a lot of the machining to bring that Zintilon bill down considerably. I could have gone without powder coating and further tried a new place with Chen and likely brought it down that way as well.
All that said, I’ve kept a lot of solid parts of the bot, namely the titanium frame pieces and lots of drive components, and if these changes do solidify the weapon, future maintenance should be far cheaper than it was here. Do what you have to do to make that happen for me. Send your thoughts, your prayers, feed your fish… whatever will work.
If you enjoyed this article, or found it informative, I have only one request: Please don’t tell my wife, she doesn’t need to know how many expensive gifts I could have bought with this money.