On Wed, 09 Jan 2008 20:15:15 -0600, Brian Whatcott
wrote:

Saran wrap is one avenue to reliable release I hear - or maybe a
good release agent - or aluminum foil I have heard suggested.....

Johnson's paste wax will work. Ask the gunsmiths about that. In
general, if there are the kind of pockets that would lock them
together, fill them in with oil base modeling clay. This is no help
with slight, just enough to cause trouble, waviness.

As for pipe for a mold, there is no taper, which is the usual practice
with molds in general. Sand castings are always tapered slightly.

Casady