Parametric Pulley with Countersink

This remix adds countersink options to the famous Parametric pulley customizer, preset for M3 socket cap screws.

Useful if the generated gear is going to be encased in a housing with smallish tolerances. Just make sure to set your nut_shaft_distance and outer diameter appropriately to accomodate the countersink. You don't want walls so thin that they can't print or that the trapped nut tears out.

An internal check requires that there be at least a 1mm wall between the outer face of the trapped nut and the bottom of the countersink.