I knew I wanted some shiplap in this room when we bought the house! However, it is a very large space and blank wall. Shiplapping this entire wall with normal shiplap planks from the store would have cost us SO much more than our solution.
We used plywood, you could use MDF as well, and cut it into strips for the planks. This is a bit more time consuming that buying shiplap planks, but it saved us a lot of money. We cut ours in about 5 inch planks. I don’t think there is a right or wrong size.
After we cut them all we stacked them up and sanded the sides and the ends all together at once. I also suggest doing this for painting the edges as well.
We used a nickel to space out the planks between each other. If you have regular shiplap planks they will fit together and space out on their own. That’s awfully handy!
The end result was worth the work! A trendy feature wall that did not cost us 100s of dollars.