I used 1/2". Mine looks pretty identical to the OPs. I tried to post a picture in my previous comment, but I accidentally posted the picture I had of his!...
I thought they looked a bit too similar
I just bought the 52 gallon [EDIT: This should be 52 quart! (=13 gallon)] version of that cooler ($31, Sears) and all the 1/2" cpvc fittings and pipe the OP has in his picture ($6.75, HD).
I'm ready to build it.
Few questions and comments:
1. You guys don't glue any of the manifold parts together? Just friction-fit?
Is that so you can clean them better? Any other reason?
2. What did you use to cut the slots? What should their width be, preferably?
How do you remove the burs from the inside?
3. I took the hinges off so the lid is detached. Cooler lids continually dropping on my hands drives me nuts.
4. Is it needed to install the bulk head valve? Any reason it should be stainless or will brass be just fine?
Reason is, I've seen some alternatives. One design routes a 3/8" OD vinyl tube through the existing spigot. It's pretty snug already but I could add some silicone to make a wort-tight seal. A small in-line valve will control the flow.
5. How are they holding up with the hot water? Any noticeable buckling or warping of the insides? Do you use a hot pre-heat before adding the strike water to volume?
Thanks for any suggestions.