In my ongoing quest to eliminate or supersede all things Matlab, I present a functional solution to the problem of extruding along arbitrary contours, written in python. This is a reaction to http://www.thingiverse.com/thing:7080, itself a derivative of http://www.thingiverse.com/thing:6923. Credit to both these authors for the concept and motivation.Parameters are specified at the top of the script. A closed curve in 3D is specified as f:t→(x,y,z) a parametric function of t. A closed curve in 2D is specified as f:s→(x,y) and is used as the cross-section to extrude along the 3D curve.Bonus : If you manually specify the "crosssection" matrix, which is a lost of [x,y] points around the perimeter, you can extrude arbitrary cross-sections.download, cut, edit, steal, modify, repost, use, go. update : I added knot.py, which simply explicitly defines the knot equations at the top and adds a couple integer parameters, similar too http://www.thingiverse.com/thing:6923.