Nail Gun w/ Nails... I used a small finishing gun with inch and a half nails
Step 1: Busting Pallets and Prepping Pallet Boards
I try to never pay for pallets you can always find them behind grocery stores, Co-ops, Wal-Mart, Construction Sites, ect. I took me about 10 pallets to do this one wall but I started out busting them with a pry bar and hammer and wasted many peices of wood before I got smart and got a buddy to make me a pallet tool (google pallet buster and you will see what one looks like). It saved time, wood, and my back haha. Once all pallets were completed time to get the nails out and it's super important to sort the boad by WIDTH. Don't worry about the length and thickness. Once completed I went over the boards with a electric hand sander just to get someone of the ruff edges and splinters off because it's for my boys nursery.
Step 2: Picking the Right Boards and Thinking Ahead
I started from the top left and went down and before I even started I knew I wanted to make sure I had the right width of boards to fit on top of the window board so I wouldn't have to do much cutting. I went to my stockpile of pallet boards and found three sizes that would fit above the window. If you have anything to frame around just make sure you take in into consideration before starting so you can plan ahead. This is my own option but the older / more used the pallet board is the better. The picture above was one of my favorite pieces due to the fact that was used before on an older pallet and someone cut the nails out but left the nail heads and it looks awesome to me.
Step 3: Measure, Cut, and Repeat
Once all your pallets are buster and boards are sanded then the hard part is over. Pick a spot to start throw a board up and nail it. After the first row just remember to stagger your cuts so they don't all line up. From here it's just measure what you need measure twice, cut it, and nail it. Don't worry if one board is thicker than the other I promise it will look awesome in the end. Beside you will never be able to do an whole wall with the same thickness on all pallet boards and in my option you don't want to. You can't see if in the pictures but some boards are a good bit thinker and it makes the wall stick out more to me. After it all was done I did go back with a broom and brush off all the dust and even use a shop vac on it. We decided not to use any stain but there are a lot of stains to choose from that would look good. I can upload more pictures on request and please ask any questions.