a pair of banquet table legs make for quick setup.
two pieces of 3/4 inch plywood to make the platform.
cut a long hole to make a carrying handle. (barely visible at top of pic )
Note: the legs are close together so one of the sets will not fold properly. To solve the issue, the left side of my bench has an extra thickness of plywood underneath. This puts the two sets of legs on different levels, which allows the legs to fold up nicely.