Customized version of http://www.thingiverse.com/thing:900277

Created with Customizer! http://www.thingiverse.com/apps/customizer/run?thing_id=900277

Using the following options:

hole_type = 0
height_of_rack = 10
hole = 2
num_teeth_or_pitch = 12
helix_angle = 30
clearance_percentage = 5
thickness = 6
gear_type = 2