making a hollow 2 piece mold

[johnny ducketts]

Guys

I am trying to make a 2 piece mold in rtv ala...dahlberg style

But i would like to cast the pieces to be hollow in the middle that way i can add a through wire, ballast, or rattles. Other than cut the master in half, is there any way to do this. I made a 2 piece mold of a nike but its a solid chunk of alumilite and casts like a brick. Any of you guys try to make a hollow 2 piece mold. Rowhunter i hope you have.

Thanks