the plinky testjig is a pcb that I made where I create two, and bolt them together with 5mm hex spacers, then solder pogopins (I forget the size! I got them on amazon lol) that poke thru to a plinky mainboard.
https://www.youtube.com/watch?v=vNIF9_tz35w
in THEORY someone could make one of these 
the advantage is that the jig can be used to flash plinky, and plinky detects that its mounted on a jig, and self calibrates all the AD/DA for cv control, and tests it, and you'll notice in the video a small 3d printed mount that allows you to place an OLED screen and so it tests all that. it also has a jack output and so on...
FANCY!