What’s the smallest controller you’ve ever used? [BitBuilt] forum user [Madmorda] picked up a cool little GameCube controller keychain with semi-working buttons at her local GameStop. As makers are wont to do, she figured she could turn it into a working controller and — well — the rest is history.

This miniaturized controller’s original buttons were essentially one piece of plastic and all the buttons would depress at once — same goes for the D-pad. Likewise, the original joystick and C-stick lacked springs and wouldn’t return to a neutral position after fidgeting with them. To get the ball rolling, [Madmorda] picked up a GC+ board — a custom GameCube controller board — just small enough to fit this project, eleven hard tact switches for the various buttons, and two squishy tact switches to replicate the original controller’s L and R button semi-analog, semi-digital functionality.

New L, R and Z buttons had to be 3D printed since the originals were fixed and needed to be dremeled out, but she was able to separate and re-use the keychain’s original button(s). After assembling the new parts and adding a shortened GameCube controller cable — so it can still be used as a keychain — the only missing feature was rumble. [Madmorda] belatedly calculated that a pair of Wii Remote rumble motors would have fit, but that’s a problem for a future version. Despite that, this is a fully functional controller — though [Madmorda] wouldn’t recommend using it for Smash Brothers.