gandalfbmg wrote:Next is I know I need to figure out what to coat these in, to protect the foam from the heat and suction of the vac table, and to give me a surface I can smooth out and fill in the gaps
Looks like you are off to a good start. I've experimented with similar things with my vac table. The pink foam bonds with the HIPS sheets I'm using and it's terrible. I haven't gotten it to work, but at least I can tell you what hasn't worked.
In the picture below you will see pink foam insulation. I tried one plain as a control, it locked in real bad, the heat deformed it too so the pull was terrible. I tried spray paint. You'll notice that the red ones are pitted where the solvents in the spray paint ate the foam away. They also locked down and deformed under the vacuum. I tried a latex paint (the white one). It didn't pit, but it deformed and locked down. I tried sealing one with elmers glue and it was probably the most succesful. It released, but the heat and pressure deformed the foam.
I've heard (but never tried it) that resin, like smooth cast 300, can be used for strength and protection in Vacuumforming. Bondo is also strong enough, but will break down under the heat eventually. It also has solvents that will eat the foam when you apply it. I've had the most success with making a mold and casting it in Hydrocal. Unfortunately I was rushing to finish this so the mold was crap, but the the vacuuforming went well.
Let me know if you want to try out my rig for experimentation sometime. It's powered off a dryer's electrical hookup and designed to be transportable.
Andy