Wow is it hot in here?....
Playing with molten metal does indeed sound fun. Makes me remember Jr. High School shop class. We used to pour alumnioum and brass. It was very fun.

There is an alternative to building your own foundry and casting shop.
There are a number of sites on the web that will give you quotes for doing one of a kind or limited runs castings. You could do the sculpting and go as far as you like in the process making the sculpted positive or even the doing it in wax. Then deliver it to the foundry.

Here are two sites I found. I don't know what they charge. You might call your local metal shop teacher. They might be able to use your project to teach pouring work.

http://www.castingsforindustry.com/
http://www.mysticriverfoundry.com/

I'd suggest searching the web for more. There appeared to be a number of them. Some pointed towards doing work for sculpters and some for industry. Some for boats. I was suprised by the number of smaller back yard operations by retired foundry workers and committed hobbists. Looked to me like these guys would be the most help

hope it helps
!RUSS