A 125 gallon tank, it's about 6 feet long, by 18 inches wide? 20 inches wide? Something like that.
Thanks for another link. You're right it's really not that pricey. I could make a wooden frame with cross boards made of 1 by 2 boards, and section it off into 2 foot sections, and use 3 sheets of that stuff an it would only cost about $30 (plus shipping on the plexi) to build it.


Fantastic link!

What sort of resistance to heat does that stuff have? It it going to cause problems with a 120 watt heat lamp?