Here are some center punches to make coin rings for the following coins: 2 Euro, 1 Euro, US Half Dollar, US Quarter, US Nickel, US Penny. The center should be drilled to the dimension of your center punch. The holder centers the coins so you can mark the exact center for drilling, which is a fairly difficult thing to be precise. There is 0.1 mm of relief around the edges of the coin but you may have to tweak the print scale depending on your printer if it is too tight. The inventor CAD files are included.
I use a very high number of shells to make a nice presentation.