In an attempt to refine my technique, I am going to scale back and try a smaller project. This is a solid plug that will eventually become the lower plenum of my intake manifold. I made it by making a mold of the aluminum flange and building a foam core. I added tubular elbow and a throttle body mounting plate. The whole thing has been sprayed with primer and sanded smooth. It's not glass smooth but pretty smooth nonetheless.

Here are some pics. This intake manifold is a multipiece design...the lower section I've made will replace this section:







Not perfect...but I can't tell you how elated I was to actually make a successful mold!!!



Fast forward...this is what it looks like and how it will mount to my intake manifold:





Is it even possible to mold this? There are some really tight crevices that worry me. I am also unsure about molding the cylindrical tube.

Shouldn't you be copying the internal surface of the original manifold and not the external surface?