Here's something you might do. Make one silicone mold. Then cast, say, five plaster fingers out of that one mold. Then hot glue those plaster fingers to a board spaced slightly apart. Then brush layers of silicone rubber onto these fingers. You will end up with a mold of five fingers, and you can fill those all at once, to make five pieces at a time, instead of waiting for each one to solidify. It may save you a bunch of time...