: Ben is right about sanding. Wait until the epoxy is cured before sanding. If
: the epoxy is green, you grind the sanding dust into the green epoxy.
: Scraping peels off material so there is no grinding in. Scraping is
: easiest when the epoxy is green AND the edge stays sharp. I scrape after
: each fill coat (except final) and I have never had a problem with the
: scraped area not disappearing with the next fill coat

Agreed, I would much rather scrape a run while the epoxy is green rather than wait and sand it down later...although this isn't really that big a deal, 2 to 3 min of sanding will take care of even a huge drip.

Where we might differ is in the scraping protruding fiberglass strands. I didn't have very good luck doing this, they wanted to fray not cut smooth. It was better to leave these till full cure and sand them off.