or a cheap, portable, hotwater device for camping. As cheap as $5 Was given this by family friend who's at Ga. Tech going for his Phd in a composite, enviro-friendly materal that acts as all structural support, insulation and finishing surface. I told him someone invented concrete years ago but then he got me with an R-value near 50 on a 4 inch wall. I do know more but he threatens to kill me! Think my son and I are gonna give this a go but I'm gonna try and use flexible black plastic sandwiched been a metal grid and see what the temp. effects are. If it works and shows promise at scale, I might place a holding tank in my basement (I have a tankless system) and pre-heat the water with solar. What this does is my tankless system has on board computer that detects incoming water temp. and then adjusts multi flame burner to give the desired output temp. If I can up the temp of the incoming water, less gas will be burned getting the water temp to the desired setting. Cha-ching! Looks like a great school project none the less!