Customized version of http://www.thingiverse.com/thing:802145
Created with Customizer! http://www.thingiverse.com/apps/customizer/run?thing_id=802145
Using the following options:
rings = 13
ring_height = 7.8
resolution = 80
ring_thickness = 2.8
largest_diameter = 118
ring_spacing = 1.4