I built one for my Diamond iX3 Batpack and just measured as I went. You may want to modify from what someone else does anyway. I cut longer than I thought I wanted and just "trimmed" down from there. Have your gear around so you can make adjustments as you go. Shoe size, glove size, amount of softballs, potential mask, and other gear you have all may make a difference in how you want the shelving to set up. The units on FB look nice, but you can make your own for under $20 easy. I used 1/2" PVC. For my shelf I used a wood dry erase board (chalkboard like) from Hobby Lobby as it was much cheaper than plexiglass. There are other materials that work too. Add a few short drywall screws and you are set.