Here is how I made them.
1. I first traced the letter backwards on the back of the piece of paper we were using for that letter. Add an extra 1/4 inch around as you are tracing. (You will need that for the edges). The letters we chose were about 1 inch taller than the paper we were using, so I had to get creative to cover both ends. Some of them I would add the remnants to the top and bottom, some in the middle, some to the top with a strip in the middle and so on. I mixed it up so they wouldn't all look the same.
2. Once you have cut out the paper and made the adjustments (if needed) you will turn both over and start adding the mod-podge to the board, then press down the paper. I would try to do it about 1/3 at a time so I could adjust the paper as needed. I would also make sure to mod-podge all of the edges after attaching to the board.
3. Next you will cut the extra edge with little slits at each corner and around curved edges so you will be able to cover the width of the letters easily.
4. Start at one end and start moving around gluing a small section of paper to the edges. This part takes a while, so be patient. The edges will not hold immediately. You will have to hold it down until the glue starts sticking, and don't be surprised if you have to go back and hold some sections down again.
6. Once dry, turn back over and mod-podge over all of the front. Let it dry overnight.
7. To attach it to the wall, you can attach picture frame hooks on the back or get some of the heavy duty Command tapes and apply to the back, leaving the little tabs hanging out the edge. I know you can buy packages of just the sticky tabs if this is the route you want to go.
Here is a look of the final product! My son does love them.
8. If you are willing to be patient in getting the letters, you can use a 40% off coupon on each of them. You can go to this Hobby Lobby website to either print the coupon or put it on your smart phone to show the cashier. For the largest letters, this will make them about $2.56 each. The paper goes on sale about every 2-3 weeks at 50% off, leaving each sheet at $0.25 each.
It is a really fun project and looks great in the kids rooms.