insulation board from Home Depot
material (about 3 yards)
staple gun and staples
razor or exacto knife
damage-free 16 lb picture hanging strips
Cost: mine was less than $40 using coupons, sale fabric and supplies on hand.
I recommend ironing your material. I did not because I don't have an iron but you can see in my images that my material is a little wrinkly. I measured my bed to see how long I needed my board to be and then used an exacto knife to cut the board down to size. The blade only cuts about half way through, and then you can bend the board over at the cut and it will break apart. After that I placed the board down on top of the material and started folding the material over the sides to make sure it was centered and fit. Once you have it all centered start stapling the material down. You want to make sure its tight enough to keep everything flat but don't pull too hard or the staples will pull out. I would do the two long sides first and the short sides last.
After you have done this to every staple let it dry for a little bit. Then turn your board back over so it's facing up. Now you need to measure where you will place your upholstery pins. I used a tape measure and chalk to mark the spots where I would place the pins. I placed my pins 2 inches apart.
Now the hard part! I used 4 hanging strips. I put two on the top corners of my board and two at the bottom corners. Place them on the board itself, not on the material. Also try to place them in the exact same place on each corner so that it's easier to measure out where to put the opposing strips on your wall. Measuring and marking the space on the wall is what I found the be the hardest part of this project. After you place the strips on your board, measure out where the opposing strips will need to be on your wall and use a level to make sure your strips are straight so your board will be straight across the top. Place the strips and then let them sit and cure for an hour. Use a level and and someone's help to stick the board up onto the wall. Good luck!