Powder molds are fine for many models, but I think it’s important to
know how to hand cut a mold (especially for some RTV molds that can’t
be powder separated). Knowing the hand cutting techniques will also
help when the molds need to be adjusted. Rio Grande has a very good
video Mold Making for Jewelry that shows the mold making process for
a number of different scenarios.
Have a delightful day!