So, maybe you've seen my Bio-Hazard Hub: http://www.thingiverse.com/thing:1704647

And maybe you thought "That might make a good coaster..."

And maybe I thought that too...actually I did!

Plus, I spent soooo much time on the design of the bio-hazard symbol to get it as close to prefect as I could, that I need to use it in as many things as possible! :) So don't be surprised if I push some more bio-hazard junk here...

It's 90mm in diameter and 5mm thick.

It's a single .stl file, but I used Cura to Pause at Height to switch the filament from black to red, 'cause it look cool...