This is a brilliant program, and it produces great 3D knots. The fact that it is free, is wonderfl. I may be wrong, but I believe, that for commercial purposes there author will require some fees, so check with the author.

I, for one, and very happy to see on-going development on this application. Some of the greatest gifts are those that are KNOT expected. This Mac user salutes you! My thanks to the developer.