I desing This coaster with 4 magnets inside and a bottle opener in the bottom so I can easy attach them to my fridge.

I have a collie so I modify this print profile but I design a bunch of 3mf file with others breads.
 

Just download the 3mf file and paint the face with your favorite colors. All the models have been design to work around 4 colors so you can use more if you want.

Pause goes in layer 21 and 46 to add the magnets. The have magnets at the top and the bottom so you can stack them together if you dont want to use them on your fridge or if you have multiple. The work really good as a coaster too I printed mine in PLA and put a super hot cup of boiling water on top and leave it there, it took around 30 min without moving the cup to leave a super small mark on the print so even if is PLA should resist enoght the heat ( I use 5 top shell to add more resistance)

The magnets that use is round magnet 12mm x 2mm