A true over-under Celtic knot and tree-ring coasters in Python (3D printable)

Using Python and manifold3d, two 3D printable designs were created: a Celtic knot trivet and tree-ring coasters. The trivet utilizes a (3, 8) torus-knot path flattened onto a plane, employing a sine wave to ensure a true over-under weave at every crossing. This method avoids merging strands into flat blobs, maintaining a solid, woven appearance. Additionally, the tree-ring coasters are generated from random seeds. Both designs are support-free and produced with approximately 50 lines of code.