...
The flange depth was reduced from 1/4” to 1/8”, pretty straight-forward.
The flange is now being cut normal to the surface, rather than perpendicular to a single plane. Not sure if this explanation makes sense on its own. The flange was previously being cut perpendicular to a specific plane to avoid having overhangs in the mold. This works for most of the flange, except for the curved section at the front of the headlight lens. In this region, there is less space for the headlight lens. Cutting the flange normal to the surface maintains more consistent space for the headlight lens. My trick was to fill in any overhangs afterwards so that the mold can be machined easily.
...