Yeah, what Ed said. Latex wouldn't be a good idea I don't think.
Also make sure that you use a good slow set epoxy that dries clear. The five minute stuff will dry very dark if you're using any color besides black. Once it's in the pin, it will just look black. I messed around for a long time with this. I did eventually figure out colors that worked in the end but found out for me, it was more hassle than it was worth.