I built this about a year and a half ago and figured I'd share so that maybe I could get some feedback from people who have done similar projects and may have insight for building it better. I wasn't really a fan of spending a full Benjamin on essentially a glorified tripod, so $25 later I built one myself.
The base is just a $20 basic camera tripod. I removed the pan-tilt handle and dropped in a 1/4-20 bolt to tighten the top in position. The rifle rest and ammo holder are just the laminate floor samples you can get for free from Lowe's or Home Depot, then covered with non-skid material that you would get for lining cabinets and the like. The "fence" around the ammo is just more of that material wrapped around 4 screws in each corner. The ammo holder is attached to the tripod post with a conduit wall hanger and tensioned with a thumbscrew.
It was a pretty easy project, and since it folds down compact like any camera tripod, it's pretty easy to carry and store. Bonus is that with the center and legs retracted, but still unfolded, it's just the right height to hold your ammo for kneeling. After a year and a half of use, it's holding up quite well (except the one flap of the top cover that unglued a day after I built it because apparently I suck at gluing things).
If I was to do this again, I'd probably replace the plastic conduit hanger with metal and dimple the center rod to hold the thumbscrew better. What do you think? Good economy or penny-wise and dollar-foolish?