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:

whole_periods = 2
segments_per_turn = 50
solid_ring = no
rail_diameter = 2
fragments_per_segment = 8
inner_diameter = 20
height = 10
top_and_bottom_reinforced = no
mirror_reinforced = yes
width = 3
turns = 5