I once thought about this too. Its more of the black top and bottom borders. You know the thing made out of plastic. Thats one thing that keeps the tank together. So if you get that out and replace it for a bigger one??? You could try making a wooden frame. Well thats just what I think. If you did attempted to do this you would need to let the glue dry for atleast a day or two and then throughly rinse out the tank and scrape off any extra bits of glue. Itd look weird though but awesome.
good luck if you ever attempt it.