Heya merpeople!

I'm thinking of making another silicone tail, and I've been sculpting things like a new fluke among others, during my time self isolating during this whole chaos about COVID-19. Those of you who've made tails, what did you use to make your moulds? I've used plaster to make previous moulds, but I want to use something that picks up detail better and produces a more lightweight mould as plaster can sometimes be heavy and crumbles as it ages. Tell me what you recommend, and any tips or tricks will be greatly appreciated!