Freakin Sweet Knots (http://knots.freakinsweetapps.com/ ) is a web app that generates Turkshead knots in real time, generating a 3D model on the screen with a few slider you can adjust to change the properties. I modeled a PLTU Lexden woggle, 3 leads with 5 bights, in a few seconds.
Shapeways to print a physical copy in the material of your choice. 3D printing is a pretty exciting technology: computer models can be printed in many different materials, and while the price of 3D printers is dropping g all th stipe, there are also many companies who will print and deliver your object to you. Shapeways is one of the oldest of these companies, and they print
in various plastics, glass, ceramic, steel, bronze, gold and silver.