Customized version of http://www.thingiverse.com/thing:16627

Created with Customizer! http://www.thingiverse.com/apps/customizer/run?thing_id=16627

Using the following options:

retainer_ht = 1.5
pulley_b_ht = 25
idler_ht = 1.5
pulley_b_dia = 20
idler = 0
additional_tooth_depth = 0
additional_tooth_width = 0.2
profile = 6
motor_shaft = 5.2
m3_nut_hex = 2
m3_nut_depth = 2.7
m3_nut_flats = 5.7
no_of_nuts = 1
nut_shaft_distance = 1.2
retainer = 1
nut_angle = 90
m3_dia = 3.2
pulley_t_ht = 12
teeth = 12