I thought the following plans for a portable shooting bench maybe of interest to some of you...
The pic below shows a mate using one I made one a couple of years back and it works very well, although the angle the photo is taken at makes it looka bit unstable when actually it isn't...
I used1" OD pipe for the legs one mine as that is what I could get my hands on, but ideally you could do with using 1 1/4" or even 1 1/2" OD pipe. It makes the legs and the hence the bench very heavy, but that adds even more stability to the design.
The pics below show the same design benches made by a couple of Americans off another forum:
If I were build one again, the other thing I would change is the shape of the top. Instead of the current "L" shaped designed, I'd make a "T" shaped one which would suit both left and right handed shooters.