hks_kansei wrote:If the tolerances are so tight, and the material easily filed/drilled/etc then won't the metal door cups just wear down the plastic after however many times of opening/closing the door, and vibration/rubbing while driving.... thus making the whole tight tolerance point moot.
Delrin is a pretty slippery plastic, and is mostly used for bearing surfaces. Wear will be minimal compared to anything else you could put there. Filing with teeth is a bit different to rubbing with smooth steel. I imagine it will be good for years.