https://www.youtube.com/c/EricStrebel more higher end molds, he does a ton of other making too.. but molding/casting could be resin, plaster, wax or cardboard.

https://www.youtube.com/c/RobertTolone MOre about the science/art of the mold itself

https://www.youtube.com/user/TheFluffinAmazin he makes mostly dice.. but its approachable.

https://www.youtube.com/c/EvanAndKatelyn not the best at it, but entertainable.. they use resin to cast but more to cover and as an art media..