"Heated" Enclosure - How much heat can a TAZ withstand?

I would like to get my own 3d printer. I saw the thread about using the TAZ box for an enclosure, and got to thinking about that foam insulation from Home Depot and making a big box out of it. Can you trap too much heat and damage a TAZ? You could even wire LEDs with an external switch and cut portholes you open up to check the job being printed.