A long time ago I purchased a watch crystal press - it is a cheap but serviceable set, yet causes me grief every time I go to use it. The crystal "dies" came packaged in a bag, and I always have to sort them when I repair a watch or replace a battery. Well, no more!

The set I purchased (Ruiha no 3174 13 piece) has dies that measure:

14mm thick (concave)
10mm thick (flat)

And comes with the following round sizes:

42/40 - 38/36 - 34/33 - 32/31 - 30/28 - 26/24

This could have been designed in OpenSCAD, but I selfishly wanted fillets.

The lid has a built in "step" to keep the dies in place when stored.