If you are making straight cuts and it is 1/4" you can typically score it with a box blade using a straight edge as a guide and snap it. To solvent weld it though, that method won't work because you have to have a perfectly straight machined edge. You can get away scraping it with a flat blade, but this manual technique isn't consistent because it requires that you remain perfectly perpendicular to the edge. The generally approved method is to use a router with a twin fluted bit. You would use a fence opposite the blade with the piece in the middle and shave off approx 1/8". That will prep your surfaces for welding. Then you have to seam the two pieces together. They need to be shimmed so that they have the exact same gap along the seam when welding. Typically you would put a series of metal pins along the seam to create a gap for the solvent to wick into the seam, allowing it to soften up the material before pulling the pins and mating the surfaces allow them to cure. There is also a very specific series that acrylic sumps have to be welded together. The two end pieces have to be exactly the same, and the front and back pieces have to be the exact same height as the sides. The top and bottom are over sized, and flush routed to make it all look right. There a few very long threads around the internet. Google acrylic pin method. It is pretty involved to get a good seam, but once you have the proper technique and equipment to do it, it gives very consistent results. If I was trying to make just one sump for the purpose of saving money, I would just go out and buy the most expensive custom sump you can find, and you'd probably come out ahead! LOL But if you want to do DIY for the sake of learning and building your own, I say go for it. It will take a bit of research, and a little trial and error, but it isn't impossible with a little bit of equipment.
