I'd like to know what you recommend to practice modeling figures?
If you're not detailed - gumpaste as it dries rather quickly.
fondant - takes days.
Can't quote on anything else
Chocolate clay is a good option. It's easy to make and is tasty. Holds shape really well. There's a recipe listed on CC for it.
My favorite is a 50/50 mix of fondant and gumpaste. The gumpaste allows for quicker set up time, while the fondant gives a little more working time. I love using chocolate clay for some things because it's so easy to use and normally requires no glue. This is my own version that I call chocolate leather though.
Another aspect to consider is that chocolate clay can be "reused". It does solidify to hold its shape well, but it can also be smooshed up, kneaded, and re-used for practice purposes. Probably won't want to eat it after several trials , but......