Inspired by an older video of Alexandre Chappel, I wanted to create my own casting mold for a jesmonite coaster. While Alexandre used vacuum forming for his mold, I decided to experiment with what I had on hand and went for a 3D printed TPU mold instead.

The coaster features a clean hexagonal shape (4.5cm side length) with an eye-catching geometric cube pattern embedded in its surface. This design combines modern aesthetics with practical functionality, making it both a useful coaster and an interesting decorative piece.

Through trial and error, I discovered that the TPU's hardness plays a crucial role in the demolding process. My first attempt with 95A TPU proved too stiff, requiring longer curing times to prevent the cast piece from breaking during removal. Switching to 82A TPU yielded much better results - the increased flexibility made demolding significantly easier. As a general rule: the more flexible the TPU, the better the demolding process.

For those looking to print this mold, I've optimized the print settings on my Bambu Lab A1 printer with the following parameters:

• Layer height: 0.16mm
• Wall count: 2
• Top layers: 6
• Bottom layers: 4
• Infill: 15%

For the casting process, I kept things simple by using readily available materials. As a release agent, I applied vaseline using an old toothbrush - proving you don't need specialized products to get good results. After pouring the jesmonite, I recommend waiting about 1 hour before demolding to ensure proper curing.

For detailed instructions on the jesmonite casting process, I recommend watching Alexandre's video linked above.