When you ask a Hackaday crowd to design a business card, you should expect to be surprised by what you get. But still, we were surprised by the breadth of entries! Our judges wracked their brains to pick their top ten, and then we compared notes, and three projects rose to the top, but honestly the top ten could have all won. It was a tight field. But only three of the entries get to take home the $150 DigiKey gift certificates, so without further ado…

Blinkencard – Pocket Altair 8800

[ajlitt] built a full retrocomputer, and a slick looking one to boot, in the size of a business card. Of course, you could run an Altair 8800 emulator on your cell phone, but without the entry buttons and real-live blinkenlights, it just wouldn’t be the same. What our judges loved most about this build was the use of an FPGA and and ESP32, for IO and storage, the reverse-mounted front PCB that doubles as a faceplate, and of course the nice 3DP bezel that hides the bodge wires from view.

BetaBoard – Tiny Particle Physics Lab

So you might have thought someone would put a retrocomputer on a business card, but a working radiation detector was not on our radar. [Tim – DJ8TK]’s entry makes use of not one, but six BPW34 PIN photodiodes, which have the benefit of being well studied in the hacker radiation detection scene. This project took a ton of design work, and our judges thought that the documentation along the way were as good as any physics lecture.

Brushless Motor and Driver Business Card Kit

And speaking of educational business card demos, [Andy Geppert]’s motor driver card not only teaches you how to wind your own coils and make a simple stepper motor, but also how to drive it. While [Andy] admits that the stepper motor design could use a few more poles for smooth operation, he also broke out the coil driver so that you can experiment by driving more professional brushless DC motors if you have them on hand. It’s a great demo, and being in a business card form factor, you can always have one on hand.

Honorable Mentions

As always, we have more awesome projects than we have prizes, so we thought we’d call out some standouts.

• Wafer Thin: [Chinchilla Optional] wowed us with this amazing dead-bug style QR code made out of LEDs. You know the card is thin when the LEDs are the thickest part. [erich.styger] contributed these RFID tag cards, beautifully laser-etched and made of 1 mm thick veneer. And bridging the Utility and Wafer Thin categories, [Maave]’s credit-card sized door entry tool needs to be thin if it’s going to work. Get this cut out of thin steel, and you’ll never get locked out again.
• Aesthetics: [BLANCHARD Jordan]’s Weather Card is cool on many fronts, but the resulting circuit sculpture combining the solar panel and the e-paper really won over our judges eyes with its understated form-follows-function beauty. On the opposite end of the spectrum, [Will Fox]’s Foxie CardClock 2.0 goes overboard with the color LEDs, and it looks awesome.

• Madman Muntz: Earl “Madman” Muntz was famous for cutting corners by removing parts until the thing broke, and we had a couple standout ultra-minimalist entries. [Adam Billingsley]’s CH32V003 Business Card targeted a $1 price tag, and this USB-capable, capacitive-touch card pulls out all the stops to get at least in the ballpark. Amazing. [Lincoln Uehara] cut corners by getting rid of the PCB entirely, and this makes his Back-to-basics paper business card friendly for younger builders too.
• Fun and Games: A business card with a working 4×4 tic-tac-toe game? [Esc]’s entry does double duty as a game and PCB design tutorial. Whether or not you should base your choice of a partner on skin resistance alone, [Un Kyu Lee]’s Doctor Love is a hilarious device, and background story. And finally, [Eontronics]’s RetroMedleyCard is an ambitious project to bring game emulation to your wallet. This project is insane, and it’s one to watch!
• Utilitarian: Our last category showcases useful cards of all sorts. From [Peter]’s Pi Pico MSP430 Debug Probe and programmable 4th Calculator to [Gangwa Labs]’s reflow hotplate (!), there’s no shortage of function that you can pack into your pockets.

Thanks to Everyone!

As always, we had more awesome entries than we have space to feature. You should go check out all the entries over on Hackaday.io. And thanks again to DigiKey for sponsoring these with prizes.