: I am building a Guillemot and need to fill some gaps between strips. The
: problem is that I built using very white cedar and need a way to lighten
: the color of the epoxy. I know that quartz microspheres will make it
: white, but is there anything else?

Be careful when applying the epoxy as filler, I just got past this step and didn't realize that the epoxy on the wood surrounding the filled area will cause discoloration if not completely removed back to the bare wood. When I applied the filler I just spread it on with a scraper and ended up with the wood covered with a very thin layer of epoxy in an area about 2" surrounding the hole I was filling. This soaked into the wood and took a lot of scraping and sanding to remove.
The advice I wish I had prior to filling the holes with epoxy was:
Don't worry about gaps smaller than a 1/16" or so and use wood slivers as much as possible without any epoxy, just your regular wood glue. The fill coat or first layer of fiberglass will cover any smaller gaps just fine.

Good luck!