Polymer class should never be baked in a regular oven because of the fumes it releases and the potential for food contamination. I have a dedicated convection style toaster oven just for baking polymer class items. Use an oven thermometer to keep track of the temperature because I have found that the settings on the toaster ovens are not very accurate. Also, make sure you have adequate ventilation in the room where you have the oven because of the fumes.
I make a lot of Steve's key chains and I use Easy Cast clear casting epoxy, clear and mixed with their fake granite powders. You can sand it level after curing and the matte finish after sanding can be brightened a bit with urethane finishes.
