Eddie,

Here's my two cent's worth. It seems that casting this is going to be difficult due to the undercuts. I don't know exactly what this is for or why it was designed the way it is, but what if you were to eliminate one or two blades so that none of them overlap each other. Then you'd get rid of the undercut and make casting this (as well as prototyping it) a lot easier.

Do a search on google for inconel casting. I do know that unless you plan on dumping a load of cash into this process, it's expensive. So is EDMing it unless you have a buddy who can do it for you.

Anyhow, just my input.

Russ