In work we sometimes use letter punches for marking metal. But it is so hard to make the lettering straight. So I designed this simple jig to help with alignment. Simply insert your 12x12 mm punch into the insert and position it to the next slot. The base has two magnets (d=13mm, h=3,3mm) used for holding to the metal plates. For storing the jigs insert, there is a snap-in feature so you never lose it. The insert has integrated springs that ensure the punches are pushed to a corner of the insert. It is important when the ends of the punches are hammered out and have bigger dimension than the middle of a punch.

Added jig for 3, 5, 7, 10 numbers - can add additional just ask for a number of letters/numbers.

Printing: 

5 perimeters, 15% adaptive cubic infill, supports only for the snap-in feature on the base