Best way to make a shoemaking last

Hi! I wanted to try my hand at shoemaking, and I want to make my own lasts using a plaster mold of my feet and resin. If you’re unfamiliar, lasts are plastic or wooden feet used to form the shoe fabric into a shoe shape. The lasts need to be soft enough to not break when pins are nailed into them. Any advice for this project? I’m pretty much a complete resin novice.