i went to revy/rona... its like home depot.... they sell this stuff thats like plastic cardboard..... cant remember what they called it but if u say plastic cardboard they will know what u mean... i paid $6 CDN for a pretty big piece... i used about 1/8th of it to divide my 10 gallon tank.... used another 1/8th to make a lid for one of my tanks... the stuff is pretty easy to cut and it works quite well