Garret Ong recently released the beginner puzzle pack which includes puzzles that contains parts that can be made with easy one part molds, and they should be a great way for someone to get started casting.http://www.twistypuzzles.com/forum/view ... =4&t=13763
This thread is a collection of puzzle that people have releases the files for free and should be a good place to get started. But be forewarned, casting isn't something that is just picked up, it takes time/practice to make good molds and to cast good parts. Don't let this discourage you, casting puzzles is very fun and the community also likes seeing a new caster on the scene.
P.S. This thread has been made a dozen times before so please search the forum before you post.