I made this Diamond Pattern Pallet Barn Door in three layers. The inside layer is 1" x 6" pine boards stained a carbon gray. I made the middle layer using pallet boards I cut in a diamond pattern. Then, I belted it with more of the 1" x 6" pine. The outermost layer is the western cedar strapping.
This Diamond Pattern Pallet Barn Door would be amazing on indoor projects too!
Here's another idea for your barn or garage - some Pallet Shelves.