Shim punch tool

I needed to make some thin shims to fit on a 3mm diameter crankshaft I am fabricating for the 0-16.5 (7mm/ft) shay model published here on Thingiverse.
The stl print file makes the base and cutting die to use the chosen sized drill (3mm) to punch tight fitting holes in brass shim (in this case - but I also used it for ptfe sheet)
The back end of the drill is ground with a concave curve across it, like a normal paper punch, and the drill/punch is driven through with a blow from a hammer WITH a piece of wood protecting the drill tip.
This design could obviously be resized - within limits.