The tabletop in the upright flat position serves as a table. However, when released from the locked, or upright position, and flipped down, it serves as a bench seat back. If a locking system is present it will have two locking pieces attached to the underside of the tabletop on opposite ends.
Two of these foldable bench pieces, when put back to back and in the tabletop position, form a standard picnic table with a top and two benches. If made from a kit or from scratch, the dimensions of the table and benches can be changed by choosing the length of the boards to be used. Underneath the tabletop or on the back side of the benches there also will be support pieces.
The individual bench seats will be the same length as the seat back/tabletops. They will have a seat brace that runs the length of the seat and connects to the legs and a supporting seat base end. The seat base end also connects to both the front and rear legs. On the top side ends of the benches are strap hinge braces that connect the bench seat to the arms that support the tabletop/seat back.
Arm supports on each end of the tabletop/seat back, along with a perpendicular table support piece, provide the support framework that connects the tabletop/seat back to the bench seat.
Two decorative fill pieces (one on each side) extend off of the tabletop section to cover the arm supports and base ends.
Each folding picnic table has a pair of front legs and a pair of rear legs. The legs are attached to the bench seat (front and back). They complete the frame of the table/bench and provide support for the bench seat.
An optional accessory on purchased folding picnic tables is a shade umbrella.
Variations in design and by manufacturer may change the position of the supporting elements or may change the purpose of the parts. For example, an aluminum picnic table designed to be light or for convenient storage may have two small individual seats on each side of the table instead of a bench seat. Additionally, the tabletop doesn't fold down to become a bench seat back. It is designed more for picnics on the go or for camping situations.