A couple of thoughts:  I worked in an office once that had an AddressoGraph Embosser, for making metal address plates.  (Similar to embossed "dog tags.")   I made a substitute date slug for an old time clock.  I think you could get the 3 characters lined up vertically, with  space on both sides. Then cut the metal, and make a sharp fold on each side of the letter, to fit the type bar.

Another thought,  a dental technician should be able to make an impression from a similar type slug, then cast it in metal.  Then solder it to the type bar,  using a lower melting point solder.  The problem here is finding a similar machine from which to make the impression.  Maybe a Corona #3.

Good luck.