What you need:
1. Wood Chip Box
2. 5" x 7" shelf brackets x2
3. 3/8" x bolts with nuts x6
How to make:
1. Remove the hinge on the wood chip box to remove the lid.
2. Place shelf brackets on back of box and mark with a sharpie where the holes are.
3. Drill 3/8" holes in wood chip box at marked locations.
4. Mount brackets with bolts/nuts.
How to use:
I would suggest draping a washcloth or the like over the runner board to protect the wood. Then just slide the brackets between the wood and the mattress, and there you go! Instant shelf!