I made a small pallet shelf to fit in a small bathroom, just so there would be some extra storage. I was lucky to find a pallet with long and wide planks, and I used those for the back. Then I ripped down a piece of a pallet that had 3/4" wood on it, and made some cleats for some extra support on the shelves. Then screwed into the shelves from the back with 2.5" screws, as well as screwing into the top of the shelves into the cleats to make sure the shelves are not going anywhere.
