Why badges still matter

“Badgelife” conference badges have become a kind of rite of passage in the hacker world. This year for THOTCON 0xD — Chicago’s notorious underground security event — I worked with my small team at Fourfold as we set out to design, fabricate, program, and ship two thousand fully interactive badges in six month’s time amidst the turbulence of trade wars, tariffs, and logistics blow-ups.

For those interested in developing their own conference badges, working with the ESP32 on a custom printed circuit board project, or if you’re just plain interested in making hardware at scale, this is an overview of our process: what worked, what broke, and why a tariff aimed at fentanyl almost derailed our bill of materials.

1. Pencil Sketches, Paper Prototypes, and a Capacitive Wheel

Every badge starts with constraints. Our initial constraints came in the form of a design request from the event organizers to incorporate the shape, look, and experience of Nintendo’s popular “Tamagotchi” game somehow into the device and its firmware. Having a product design background, I know that diving into paper cut-outs – rather than acrylics and code – allows you to iterate the ergonomics in hours instead of days. Paper prototyping also surfaced an insight: a dial would fit nicely on the egg-shaped silhouette and give us a range of interactions that simple buttons wouldn’t.

Working with the paper, it became apparent that a physical dial wouldn’t be as ergonomic as a touch pad one. It also became apparent that, due to the nature of the surface area of an ovoid shape, we’d need to go with a smaller rectangular screen. So, we decided to drop a capacitive touch wheel from an old Texas Instruments design around a 1.3" IPS TFT screen, powered by SparkFun’s ESP32 Thing board. The wheel became a two-in-one UI — menu and game control — without adding a single moving part. This had a cool iPod-like retro feel to it and saved us significant money to boot.

Hackaday-worthy takeaway: Don’t obsess over CAD in week one. Paper shows you if the interaction is fun long before Fusion knows the board outline exists. I use Strathmore 300 Series Bristol Paper to do a lot of my early prototyping – its rigidity lends itself well to making manipulatable objects. I also use rolls of White Kraft Paper as well as Strathmore Newsprint pads for plenty of surface area when it comes to sketching.

2. PCB Design in the Tariff Era

Component shortages aren’t over, they’re just weirder. The new tariff package hit just as we were getting ready to bring in boards and components. The screens that we shipped in for the badge cost a total of around $6,000, but were initially coded as televisions and hit with a $10,000 tariff. After 16 hours on the line with DHL, we were able to get the screens recoded and only ended up paying $4,500 on a fentanyl tariff.

With the screen problem taken care of, we turned to the rest of the board layout. Remember that touch wheel? Texas Instrument’s parametric CapTouch template came in handy here for a few reasons: 1) It only took up three pins on the ESP’s board, and 2) it knocked $4.38 off every badge that we would’ve had to spend if we’d gone with a traditional dial. Multiply that by 2,000 units and the “small” change is real money.

Because the template was parametric, we could script the wheel’s diameter instead of redrawing it each time the enclosure shifted. Seven script cycles landed us on a 32 mm wheel perfectly nested inside our oval—clear of the TFT ribbon and every mounting boss.

Copper thickness was the last silent negotiation. Too thin and the wheel’s resistance drifts with Chicago’s spring humidity; too thick and we blow the cost target. The sweet spot: 1-oz copper with 8 mil traces and gaps, keeping series R under 50 Ω without torpedoing the budget.

With the board design dialed in, we sent it off to our turnkey solution partner...