Module figure8_profile 

A “figure-8” / dumbbell solid with two rectangular holes running all the way through it.

This is just an outer footprint and two hole footprints (a dumbbell outline — two square “lobes” joined by a narrow neck — with a small square hole in each lobe) handed to extrude, which does all the actual euler-operator work (including the holes, all the way through both caps and their own side walls).

Functions

figure8_profile

Build the figure-8-with-2-holes solid: outer_polygon extruded by one unit along +z, with hole_polygons cut all the way through. Returns the new solid.

hole_polygons

The two square holes (one per lobe), each as a CW polygon in (u, v) parameter space.

outer_polygon

The outer boundary of the figure-8 profile, as a CCW polygon in (u, v) ∈ [0, 1]^2 parameter space.