Prototyping is a personal affair ... footprints for microcontroller boards, an Arduino shield, a Raspberry Pi header, and much more. There will doubtless be ones that readers will spot as missing ...

Not much, but that’s all you need for a prototyping board. The bootloader is handled by [Maniacbug]’s Mighty 1284 Arduino Support Package. This only supports Arduino 1.0, not the newer 1.5 ...