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.

I would do it as a 2 piece mould, straight down the middle. The tube looks like it is offset a little bit but that shouldn't be a huge issue, just have your barrier follow it. 

Made some slow progress...flanged up with fillet wax:

Backed it with 2 layers of 3/4 oz and 2 layers of 1.5 oz. 

Progress!

How do you effectively seal the joins in your molds for vacuum infusion?

Envelope bag.

I won't be able to mold this as a one piece unit. The shape is too complex.

It will have to be two separate pieces that are then bonded together. <-- This is what I am most nervous about. I don't know how to prepare the bonding seams on the two halves of the final part....and, Easycomposites won't post the 3rd and final video in their series on complex multi-part molds which shows how to do it(((

Will the two halves be glued edge to edge, or is there a flat mating surface?
In the former case, have a look at the RC model crowd building techniques. If it is the latter then you can include some peel ply in the laminates covering both bonding surfaces. The peel ply is thenremoved from the parts and you can glue them together.

Thanks for the reply. I will have a look at the RC forums.

The two halves will be glued edge to edge. This will require precise trimming. The flanges at the trim lines take off at 90 degree angles. I'm guessing I would trim the excess with a cut of wheel and then just try to block them down as close as possible.