of the thickness of the main wall to prevent sink marks on the exterior surface.
The gate—the tiny opening where molten plastic enters the cavity—controls everything. Too small, and the material freezes off before the part fills (short shot). Too large, and you can’t break it off cleanly, or you pack too much pressure into one spot.
A simulation will predict:
Molded-in textures (like leather grain) require 1 additional degree per 0.001" of texture depth.