Aluminum foil reels have to be preheated for manufacturing but it's inefficient (the doors aren't sealed and the material isn't in close contact with heating elements at the sides). I'm considering an initiative of more efficient design. How difficult would it be to evaluate heat transfer if each real is also in a plastic bag (so I have to consider different mediums)? Since it's aluminum foil I guess I should go with conduction and try to design heating elements tightly around each reel. The goal is to heat the the material fast to 50C thoroughly but never going over 60C. I'll also have to consider rate of return, you think such custom design would be expensive?