Mark I

The first attempt at this was made when I was only using small Arduino clones, some Teensies and Trinkets, and an odd STM32 board. All of those boards had the same width, so my first attempt only had two rows of female headers:

(The holes are there only to make it look cooler.) The connections are pretty much what you would expect from a servo breakout:

The dimensions are 5×5cm, the largest I could get made for cheap.