We had the need to test a custom module that came back from assembly. The module is meant to be soldered onto another PCB via castellated pins and is very small.

As holding a multimeter probe (even if its a PCBite) would be a nightmare for more than one piece, I designed a little test jig that uses 0.7mm (!) pogo pins (MPN: 1007-D-0.7N-AU-0.49). The pogo pin holder is 3d printed with the 0.4mm standard nozzle diameter and surprisingly comes out well. Even if it's hitting the resolution limit of the Prusa.

Soldering process: