Portable shooting platform
If you are not shooting well on a day, how to you diagnose the source of the problem? There are many variables that influence the accuracy of a shot. It is important to eliminate the variables in a systematic way to single out the few that actually matter.
One variable is the stability of the "shooting platform." Even in a hunter class set up with a stool and a bi-pod, it is still not stable enough to eliminate the platform itself being a contributor to scattered shots.
There are many ways to remove the stability of the shooting platform as a variable.
Manufactured tripod with two support points.
Caldwell (now BOG) Deadshot FieldPod: Very light and portable, sturdy for its size and weight, and highly adjustable. However, it is fairly short and is only good for low sitting positions. There are two bigger versions, Max and Magnum. The Magnum is tall enough for standing positions, but rather heavy and difficult to transport. The Max is a good tradeoff.
Manufactured tripod table/bench
MTM HLST (high low shooting table):
instead of offering two support points, there is a whole table top so bags or other supports can be used, a flexible option for both piston and pneumatic guns, rifles or pistols
About the same price point as the Deadshot FieldPods.
Good bang for the buck
Not exactly portable or light, but probably "luggable" enough just moving up and down a range
Cannot be set up on concrete because leg joints have not stops, and spike shoes.
Caldwell "the Stable Table"
includes a height-adjustable chair
definitely heavy and not very portable
Pricier than the HLST
More bench top area
Not as adjustable as the HLST
Can be set up on concrete
Heavy duty photography tripod + 1/4-20 to weaver adapter + bottom weaver rail
Can be very stable, but probably not suitable for piston guns
A good photography tripod can be expensive if it needs to be bought, the Bogen 3001 "legs" are somewhat economical choices
A good ball head with tension/friction control is recommended, this can potentially cost several times the price of the legs
Can be quite expensive compared to the other options
Best option assuming ownership of tripod and ball head, plus a pneumatic gun
Shooting in prone position with a bag
Almost free or completely free
Prone position may be too low depending on vegetation growth
A little cumbersome for piston shooters (to cock the gun)