Tunable Tolerance Tetrahedron Twist Timewasting Toy

This tunable tolerance tetrahedron twist timewasting toy thing was inspired by http://www.thingiverse.com/thing:186372 . The problem with that thing was that it was just an STL file, with no means for adjusting the "fit" tolerance or scaling. So, one of the students in my lab, Zachary Snyder, spent valuable should-have-been-studying-for-final-exams time on deriving his own formula for it in OpenSCAD... and then I spent too much time trying to print it with various parameters and tweaking the de