Re: DIY Rack... Whoo-Hoo!!!
Dado cuts are fine for PVC. I use it on all of mine. Here's the rub though. There's a fine line between getting it right, and having a melted mess on your hands. Aside from that, it's doable and makes for a much stronger design. You can do it with just the screws, but remember that the PVC is a softer material. It will benefit from the joinery and it adds a cool factor, and makes it a lot easier to assemble. Granted I am using a CNC table, but a router will get it done IF you use a guide. That's a must. AND remember that the PVC cuts like butter. Get it right on a piece of wood first. Also, don't make the span of the shelves too long or wide without support. It will sag if you are not careful, even the 12mm or 1/2 inch stuff. BTW, use the 6mm or 1/4 for the backing and save some $$$. It's not structural.
EDIT TO ADD. Don't use the 6mm for anything else besides the backing. It's too thin. The OP is right. Use the 12mm for the strength.
Dave
Re: DIY Rack... Whoo-Hoo!!!
I got mine xpvc from a national plastics company and they cut it to size for free. I am not sure about the channel cut though. Not sure if they would do that. I used screws and it went together fine. I was thinking of glueing it also, but couldn't figure out how I would do it without making a mess. I think I would have had to build it, take it apart and glue one side at a time. Didn't seem worth it. Mine used three sheets and cost me 350 and some change in black. For my first time using this product it turned out decent, only one shelf was way to tight until I figured out the spaces I wanted to use. Would I do it again? Yes, I got an eight high rack with tubs for like 425. I did use solid sides to hold heat, so that was a lot of the cost. If I used strips it would have been way less. Mine is a 41 qt and I do have one 170 gram male that seems to do fine in it.