Re: 60g Paludarium w/ waterfall and bog - build log
Indeed. I have never tried that with a heat gun. I rarely use egg crate, but you've inspired me to reconsider ways to utilize my poor, neglected heat gun. Ha ha ha. Give a man a tool, and look out!
One way I have used it is to harden carved foam before applying epoxy or Drylok. You can create a tougher "outer skin" to your foam.
I'm not sure what sorts of nasty chemical transformations this treament may be forcing - I just always cover the heat-treated foam with a waterproof coating. I also don't heat long or hard enough to get ignition or smoking, but...the plastic does change significantly. And there's a little stinkiness that comes off the job.
Besides hardening the carved foam, this heat treatment also softens sharp carved edges, and causes a lot of "pills" to shrivel up. Sometimes the former soft "pills" become more like hard, sharp little "prickles" but those are easily nipped off flush, with toenail clippers or wire nippers.
Anyway...have fun, good luck!