Unfortunately, the two reusable molds I know of (Composimold and Amazing Remelt) appear to filter UV light just a little too much.
I’ve experimented a lot with Amazing Remelt, and it can never quite cure the resin all the way. I even tried using completely clear UV resin on something about the size and thickness of a key, and it was still only half formed after an HOUR under the UV lamp. A nearly identical sized mold cured prefectly in 3 minutes in a clear plastic mold.
I haven’t tried Composimold, but I’ve heard it has similar problems of not being quite translucent enough.
If you HAVE to use it… it CAN be done. you just have to do paper thin layers of the UV resin, curing for 2-3 minutes each layer.