So here's the situation. I have no dough for more polyurethane casting and I'm being asked to sell castings. I have a couple good ones but my casting supply is running out. Without a pressure chamber I'm making heads with one or two small divots. I have clear epoxy resin I bought a while back and just started casting (slow cure time so I am not sure how they turn out but I am feeling good that the air issue will be better because of the slow cure). My question is, which is better as far as strength and appearance? I have this feeling epoxy may be really nice but I notice most casters use polyurethane or the polyester from alumilite. Is there a reason why no one really uses expoxy resin?