I needed a small cabinet (no door) for bits and accessories near my drill press in the garage where I do my metal work. When we bought this house I removed a bunch of long shelves on one wall of the garage which had been there since the mid 50's. These old shelves have been on sawhorses behind my woodshop for well over a year now but I decided to see if they were good enough to recycle into the small cabinet which I needed.
The shelves turned out to be rough cut 1 x 6's which were a uniform width (6 1/16") but thickness varied from 7/8" to 1 1/16". To keep things simple I just cut seven 15" lengths, which required me to get one from a second board (shelf). That board was warped, cupped, twisted, bowed and tapered in thickness.
I decided to use the boards as they were, rather than plane them to a uniform thickness, partly because of the lead based paint and partly because the paint matched what was on the wall it would be mounted on. I ended up drilling 4 pocket holes in each end of all four shelves and two in each end of the two mounting cleats (40 pocket holes in all). I set up for 3/4" boards which worked fine but I did have to constantly adjust the clamp on my K2 because of the varying thickness from one edge to the other of the boards. Of course I did not attempt to use glue on the old painted lumber.
As it turned out one of the boards was pine, the other cypress. There is no reason that this should have gone well, but for some reason it did. The little cabinet came out nice and square and since the material was painted at the same time as the rest of the garage it looks like it has always been there. This is not a high quality, furniture grade project that would be worth bragging about but I thought that since it came together so quick easy and well, even using material that was not up to standards, it might be worth mentioning. It does show that the pocket hole joinery does not always require precision machined lumber, in this case there were no joints where the varying thickness of the lumber would show or matter. This is one time that the Kreg K2 really did the job