When I first started fiddling with designing and building electronics this was my go to. First model is based off an Instructables 4x4x4 cube design that has an external arduino to control the 16 columns and 4 ground planes. The design was fun to start with but rather messy in it's presentation so I went and designed an integrated board for the whole thing. PCB design was done in EagleCAD, PCB printed via Seeedstudio Fusion PCB. Second model has an embedded ATMega48 (probably poor choice in hindsight due to 4kB flash) with standard LM7805 lin. reg, ICSP header and optional external oscillator.