Customized version of http://www.thingiverse.com/thing:41520

Created with Customizer! http://www.thingiverse.com/apps/customizer/run?thing_id=41520

Using the following options:

free_height = 60
build_space_between_washer = 1
free_od = 30
build_size_width = 1
free_id = 10
washer_sides = 128
sizeM = 2
tolerance = 0
build_size_depth = 1
freemode = yes