Btw, I wanted to add that the biggest issue I had while replicating
@ChinaVoodoo ’s invertebrate kiln was cutting the 2” XPS foam board cleanly. If I was doing it over again, I would have used one of my fillet knives (for cleaning fish) to make the cuts. I used a fillet knife to cut the hole out of the side where the wires go and was happy with the results. I tried utility knives, pocket knives etc., the cheap break away utility knives are what I did most of the cutting with. These can provide a very clean sharp cut but they dull very quickly and you must stay on top of that. It may have something to do with the fact that I used the 250 xps rather than the 150 (same R but 250 provides greater compression strength of 25 psi vs 15 psi) anyway, most of my cuts came out sloppier than I would have preferred, leaving more gaps for me to fill in during the construction of the box phase. Fillet knives are generally extremely sharp, thin (very important) and long making them the perfect candidate for such a task. In the search for the perfect foam board clean cut I have heard of many different methods. Turning the blade around on a circ saw, etc… the perfect tool, in my experience, is an extremely sharp, thin, long blade.
Edit: I used to have some disposable type scalpels but could not find them during construction of the kiln! A scalpel would be perfect due to thin handle. An exacto knifes cylindrical handle would get in the way when the cut must go deep into the foam.