casting of molds

Hi All:
i have a question. I’m making a mold of a yoke for a friend of mine who’s building a flight simulator from a 747-400. The housing also needs to made as well.
We have completed making the molds, we plugged the holes to be drilled out later.
The question is, how can I put a cavity for wires and some hardware on the inside of the housing, and yoke. for the yoke, i was thinking of a copper tube, but I don’t know what for the housing. The housing is pretty big. It’s a 3" diam. with a 90 degree elbow. I want to try to avoid casting 2 parts. Any suggestions?
7474
spitpilot40@hotmail.com