Customized version of http://www.thingiverse.com/thing:45950

Created with Customizer! http://www.thingiverse.com/apps/customizer/run?thing_id=45950

Using the following options:

solid_ring = no
fragments_per_segment = 8
whole_periods = 3
turns = 5
inner_diameter = 16
segments_per_turn = 50
width = 2
rail_diameter = .5
mirror_reinforced = yes
height = 5
top_and_bottom_reinforced = no