This is a remix of a Blockmit. I am using 8mm punch and a ½" flat washer 1.25" O.D.
Also here is a 1" insert for 1" O.D. washers.
A 1" center wheel is needed to work with the washer insert.
Added a center wheel with both 1.25" and 1" punch holes.
The author remixed this model.
Scaled to fit Harbor Freight Horusby Number & Letter stamp set. 37 Piece. Letter at 6mm steel punch at 8mm. See picture.