I turned a 10 gallon into a sump for my 46 bowfront a few years back. Got my ideas from melevsreef.com He's got some great ideas, diagrams, and instructions. And there are tons of folks on here that do it as well. If you click on the "convert a 20 gallon into a sump" you'll get the general idea. You can get sheets of acrylic from any hardware store in various depths too. He's even got info on cutting teeth.