Here is a metallographic sample holder. It aims to save space and ensure samples don't get scratched during transportation.

Note that the inner core needs to be printed horizontally so that the layers run vertical (Parallel with applied force)

The fusion360 files are parametric. The sample diameter (max 32mm) and length and cap scale can be adjusted: https://blog.prusa3d.com/parametric-modeling-in-fusion36

*Note that the cap is the same size for different sample diameters. One can play around with the scaling to achieve the proper tolerances.