I just uploaded a library to Thingiverse for creating parametric involute spur gears using list comprehension (instead of my old library that builds a half tooth, and uses transforms to rotate and mirror and unions to duplicate the teeth). http://www.thingiverse.com/thing:1919326 I would think this should be much quicker than the old version. It also is as simple as possible. My old script had all sorts of arguments for the hub size thickness and hole size, and parameters for the rim and other holes through the gear. The new script just creates the 2D involute gear polygon and leaves the rest up to the user. I think this works better for a library. It's my first project with list comprehension, so I was wondering if someone more familiar with LCs could look at shout out "your doing it wrong" if there are better approaches. Thanks, Greg Frost

 gear_points=flatten([for(i=[0:num_teeth-1])

 gear_points=[for(i=[0:num_teeth-1],

I haven't seen anything wrong or any inappropriate use of LC in your code. Whenever possible I avoid to use flatten. For instance, instead of : > gear_points=flatten([for(i=[0:num_teeth-1]) > rotate_list(-360/num_teeth*i,tooth)]); > I would prefer: > gear_points=[for(i=[0:num_teeth-1], > tooth_pt=rotate_list(-360/num_teeth*i,tooth)) tooth_pt ]; > I don't know the gear profile generation techniques but your code seems to be clean and well commented.