Celtic Cross

I am uploading this design in honor of St. Patrick's Day.

I saw the "Celtic Crosses" Thing by jpearce (linked), and couldn't resist doing it my own way.

This is another product of my Bezier Curves script for Blender. (http://www.thingiverse.com/thing:56629 ) This is a somewhat more complex application than I have attempted so far, and I am pleased with the result. Actually, generating the geometry for the braids was the easy part...

What I've struggled with is to "clean" the meshes that Blender produces. The knot meshes are self-intersecting, and Blender tends to produce non-manifold geometry in Bezier curves. After fixing the manifold issues, Blender still fails in boolean operations with the Bezier curve meshes.

I have tried to clean the meshes in MeshLab also, but without success. It can select and delete non-manifold faces, but that leaves holes in the mesh, and the automated hole filling tool has not yielded satisfactory results. I found a way to remove hidd