tackleunderground.com
I don't know much about soft plastics. I do know that you can melt down zoom and stuff in the microwave in a pyrex glass. You can also make molds from a variety of materials including rtv silicon and plaster of paris (POP). But check out the website. I'm strictly a hard bait builder (swimbaits and cranks) so I don't tap into the soft plastic thread much. There are also tutorials listed on the site that you can download to get you started. If you have a question someone will have an answer... those guys are geniuses