My latest creation is the three dimensional Trefoil knot. I designed it in such a way in OpenSCAD that if the parametric equations are known it’s easy to implement in the script. It was printed without support and the result wasn’t too bad. The surface is a bit rough but I’m confident that I can improve that with MeshLab.
If someone wants to tinker with the script or 3D print: https://drive.google.com/open?id=1Fht626tkD747crsAx_46S6G419AmDGD5
Beware that rendering can take a considerable amount of time.
Here is a link to my YouTube video where I explain how it is made in OpenSCAD: https://youtu.be/cGZjWD5ebHc