Customized version of http://www.thingiverse.com/thing:220935

Created with Customizer! http://www.thingiverse.com/apps/customizer/run?thing_id=220935

Using the following options:

axel_diam = 8
hole_sections = 12
bar_snap = 0.4
tread_sections = 40
wheel_diam = 200
post_base_corner_r = 14
bar_d = 2.2
bar_space = 10
center_post_diam = 12
center_post_h = 46
wheel_thick = 1.6
wheel_cage_clearance = 11
o_corner_r = 1.5
wheel_depth = 80
hole_coverage = 50
i_corner_r = 8
back_thick = 1.8