Quote Originally Posted by Bimmerstyle View Post
You don't have to sand the structure out of these materials. It's, as you say, virtually impossible.
The issue I have with fillers and maybe it's just the ones I've used is they seem easily scuffed.

I experimented with poly fillers a little, but had some bonding issues. IIRC, some plastics have the outside flame treated (can't recall the process name) so they can be bonded to better. I tried this myself with ginger use of a blowtorch and did have much better results, but I never did much more than experiment.

Nice work btw.