A retro classic is to use real 5.25 inch floppy disks as coasters. If you don't have them, now you can print them. I was suprised that nobody had that idea yet and I did not find any other 3D model of the floppy disk, so I had to do a bit of research for the exact measures, and [https://www.brutman.com/Diskettes/Diskette_handling.html](https://www.brutman.com/Diskettes/Diskette_handling.html) seems worth a read if you are interested in more background.