This is a transparent drink coaster I designed for Valentines' day drink.

I experimented with the Bambu Lab transparent PETG for the base and the red heart pattern is printed with basic red PLA. The red heart pattern is embedded inside the PETG base, so it will not melt with a bit higher cup temperature. Also, you have more color choice for PLA for inside heart pattern color. It turns out pretty good with two different materials.

The Bambu PETG transparent material did a decent job. I followed most of the setup in the wiki page: Printing tips for transparent PETG | Bambu Lab Wiki

I also provided a printer file with base and heart both use PETG filament.

The coaster has two size. Larger one diameter is 4'' for normal glasses and smaller one is 2'' for tea cups.