@Cherokee @L Ross You guys kinda got me thinking, I am overthinking this.
There is one thought that just crossed me. Aluminum draws heat. It is used in electronics, as heat sink material. When I used to play with soldering a lot, way back when you could buy components and fix circuit boards, used aluminum heat sinks to keep the heat from burning out the new transistor, ect.
Why would not laying an aluminum mold directly on the coils be ok? It is a diffuser, so their should be no need for a diffuser. Maybe with steel but not aluminum.
Just checked my aluminum molds, not a circuit board or transistor in any of them.