This is from a post by Oscar Duran in Home Gym Community by Garage Gym Reviews.
"It’s a good weekend job. I picked up a ton of old pallets that were going to be thrown out. The hardest part, believe it or not, is breaking them apart. I bought about 4 different stains and stained the ones that weren’t weathered. A lot of them had different weathered colors already. Then I just used liquid nails and a nail gun (real thin nail) just to hold them up till the glue sets. If you want to go the extra mile then you can paint the wall black first. The pallets will always have little spaces and you’ll be able to see the wall a bit if it’s a light color."
I have also seen an example where the installer set a horizontal line in the center of the wall and then vertical lines on the stud centers. He then set the middle row and worked his way up and down and created a really nice effect as well.
I think this would look really incredible.