I built the oven for the foam latex Frankie last night. It's made of that foil-backed foam in roughly a 2 foot cube. It fits around an old electric stove top. So far, it looks like I only need one burner to get it up to ~180°F.
The mold will sit on this rack:
That thermometer sitting on top turned out to be unable to handle the heat, so...
And this is the steampunk side....uh, I mean the thermometer side ;)