My son wanted a Celtic knot bracelet. This library was used to create my first attempt. The library contains a couple of examples at the top with some example patterns. The latest version will be on github at https://github.com/beanz/celtic-knot-scad The API is still work-in-progress so expect changes. Feedback would be much appreciated so that the API can be firmed up sooner rather than later. For the next iteration of the bracelet I'm planning to create a celtic knot font of the tile alphabet for http://www.thingiverse.com/thing:16193 so then it should be possible to "draw" knots on cylinders and spheres too. UPDATE 2014/02/02: Removed use of children() which isn't supported on older versions of openscad.