I think 144 RPM would be too fast. I made mine from an old BBQ rotisserie motor, it turns at about 40 RPM.

I see these often at the thrift stores for about $5....

Quick set epoxy, like the 5 minute stuff will be less transparent than the 20 minute types. It also seems to trap bubble and not spread as evenly. The yellowing that occurs with some epoxies is from contamination, for a crystal clear finish DO NOT mix with a wood implement (like a tooth pick) and do not mix it on paper. Use a plastic straw and mix it on a piece of alum. foil.