you might want to take a look at this article on about.com http://saltaquarium.about.com/cs/aquariumdiy/a/aa120897diyaq.htm
it references some dimension calculation tools. It seems that the most important aspects are going to be in the thickness of glass you choose and the sealants. (or maybe...
Hi Baptist, you can try looking through some of the online fabric stores such as http://www.pmquilting.com/ and http://www.fabricplace.com/scripts/jobs.asp.
Good luck!