Physical bitcoins are a USB based bitcoin storage device for gifts or a way to create redundancy in backing up wallets. Its purpose is not to be a single way to store a wallet since USB drives sometimes break.

The printed case makes it easy to identify the drive and makes it hard to lose, an improvement over a standard USB drive.

https://www.youtube.com/watch?v=dFqKfF2KQj8

This was printed this with a layer height of 0.3mm with yellow ABS plastic, Infill of around 20%. The USB drive is secured with a small spot of hot glue.