Hi Pat,
I don’t have a molding material recommendation but for the resin itself, if you are mixing and pouring three ounces of resin or less at once, the Resin Obsession super clear resin works great. It’s in our store here:
https://shop.resinobsession.com/collections/resin/resin-obsession-super-clear-resin
If you are mixing three ounces or more at once, then the deep pour resin is a better choice: https://shop.resinobsession.com/collections/resin/resin-obsession-deep-pour-resin
Both are meant for molds and cure hard and durable.