This model was made in Tinkercad.

To customise the coaster follow these steps: 

1. download STL file and open in your slicer
2. open the print settings and go to top and bottom layers
3. set top layers to 0
4. pick you infill pattern and density (20% works well)
5. slice and preview your model and change infill to preference 
6. print and enjoy :)
7. (print time will vary depending on infill type and density)