Do you CPOP? I do sometimes, and use one of the aluminum trays that you use for a hot buffet table filled with water on the lower rack in my oven. I wonder if you could do something like that by filling an aluminum pan with hot water, cover it and put the mold on top and then insulate with a box and towel. It won't surround the mold but it will retain heat. They sell the pans with lids at the dollar store.