The $10 Four-Key Macropad

Macropads — custom auxiliary keyboards meant to enhance your productivity — can be a great investment. At the same time, such devices can easily cost $100 or more, a good chunk of change for something you don't really need. Toby Chui's single-IC, four-key mechanical macro keypad, however, costs a mere $3 to manufacture and sells for $18.98, in a large part to compensate for expensive international shipping.

Along with a minimal number of keyswitches, the reason for this device’s low cost is that it uses a single inexpensive chip, the CH552G, as both a USB interface and its overall controller. The keypad can also accommodate optional LEDs (or perform other IO tasks) thanks to unused GPIO pins on the CH552G.

The macropad is programmed via the Arduino IDE, but as most will have no experience with the CH552G, Chui has created a companion webpage interface to automatically generate Arduino code. You simply take this generated code and upload it to your macropad for an entirely customized experience. For even more functionality, you can also integrate this device with an interface automation program like Autohotkey.

While it's sale on Tindie, the macropad was ultimately designed as a gift to exchange in person at Maker Faires. Given the manufacturing price, this seems quite generous, though not outlandish. Note that the demo version features a 3D-printed base to display components, but what’s shipped will be a non-transparent PLA version.