Its not easy. I built a overflow box still trying to get it done. I'm about to build a sump but I got a friend from work that is helping me he has a metal shop at his home business and has cnc machines and said he would cut the acrylic for me.
Lowes has 1/4" 24x48 sheets. Lowes will cut it but they are really rough cuts. Well they are smooth but its not even. There are some other places around Atlanta that has it. There was a thread about it on the forums I'll see if I can dig it up.
The main thing is smooth clean cuts. What kind of tools will you be working with?