4chord MIDI By Sven Gregori (CrapLab) · Example build · 5 views · 0 remixes A tiny USB MIDI keyboard with just four buttons, one for each chord of the I-V-vi-IV pop progression, in any key 0SaveRemixCopy link Estimated parts costNo price seen yetDifficultyModerateParts2 parts · 2 pcs Start the assembly guide →