I created a simple cross thread coaster where I wanted it so more than one can be made to interlock with each other.

I created these using PLA though support material was used to support the structures and ironing was set to improve quality.

You can use PETG if you need better heat resistance though I had no issues with my PLA coasters

It takes on average 2 hours and 30 mins to complete two.

The photos show the interlocking work. I will note that they can be tight to fit I have provided the step file if you want to remix I don't allow these to be sold unless permission is asked or you email me a proof that you have donated at least one British pound to Epilepsy Society