About this 3D model

This version adds customizer support. Note that you may have to rotate the customizer view a bunch of times for the pattern to display properly. (It looks like customizer does not like looking straight into a cut.) Like the original version, some versions of Repetier Host require you to do a "fix normals" on the generated STL to allow the whole thing to print. EDIT #1: Change the big number variable to not depend on layer height, in case someone chooses a miniscule layer height. EDIT #2: Allow setting number of rings to 0