The test fixture was similarly expedient — just a piece of wood with a hole drilled in it and a wrench holding a nut. The screws were FDM printed in PLA, ten in total, each identical in diameter ...

this metric screw generator will do the trick for screws between M2 and M16 with matching nuts and washers. Fastener hardware is pretty accessible, but one never knows when a 3D printed piece will ...