Removed the metal strip used for forming the edge. With clear packing tape on the metal strip, it just popped off really easily. Trimmed the epoxy build-up on the lower side. This trimmed and sanded fairly easily. Mixed 1 more pump of epoxy / filler and laid this onto the upper side. One lesson learned - use less epoxy so it builds up to a thinner layer. This leaves less to sand down. Left the part over the space heater. It's an oil-filed heater that only makes about 120 degree air.
