I built a great one a few years back and put it in the ground. I had to sell my shooting range property, so I cut the legs down and haul it now. It's a bit heavy, but one guy in shape can roll it in and out of a truck bed. I got the plans on line, and when I get home I'll send you the link.
Here is one I built out of a piece of 3/4" plywood, cut wedges from a 2x4 for the angle of the legs, attached 3/4" pipe thread floor flanges and 6" x 3/4" IPT welded inside some light weight 1" tubing. The legs just screw on and off, the whole thing weighs less than 25 lbs.
Not as steady as a concrete bench rest, but I managed to kill an antelope at 847 yds in Wyoming on 1 Oct with it.
"How a politician stands on the Second Amendment tells you how he or she views you as an individual... as a trustworthy and productive citizen, or as part of an unruly crowd that needs to be lorded, controlled, supervised, and taken care of."
--Rep. Suzanna Gratia Hupp (TX)