Thanks much! didn't think a heat gun would produce that much heat. The gun locker is a good idea, have seen several on the web like that. I have 40 boards of ridge RMAX Plus 3, but it is only rated up to 250F. I thought about the old stove insulation, but it isn't ridge and it's bulky. There is also n insulation used in vehicles that I saw saw in DiY ovens, but expensive for the amount I need. I am going to contact McMaster CARR. They have insulations that will cover just about every application. Then have to look at how much it costs. I thought about the old stove insulation, but it isn't ridge and it's bulky. I need one layer of insulation glued or screwed to the inside walls and don't want to encapsulate it. After I find a suitable insulation and assemble everything I'll post the information. Thanks again.