Building a Sump

[SpateD]

I'm building my first sump on my own. I have bought 6 - 2' x 4' sheets of acrylic, a plastic cutting knife and am looking for some Weld-On currently.

I plan on routering some of the parts of the acrylic already, but I'm not sure how to actually cut the plastic. I know using the knife with a straight edge and breaking it is 1 option. But I can't seem to get it to make a perfectly straight line so I haven't started cutting yet.

My only dilemma thus far is that I planned on my sump being 12" wide and I have a 24" sheet. So if I can cut that sheet exactly in half, I can use the one half for the bottom, and the other half for a 1 piece Euro Brace. I also plan on making the sump 42" long. So I don't know how well a scoring blade will work to go completely through the acrylic sheet to slice it right in 2.

Does anyone have any idea's on how to make a perfect cut without losing a few 16th's of an inch for a regular saw blade?

Also if anyone around the Lethbridge area knows a place to purchase Weld-On #3 or #4, or even #16, I would be very thankful for the help.