To make a foldable picnic table bench, build the table top; build the legs and lateral support board; paint the top, legs and lateral support board; and join the top and the legs. Be sure to sand and prime the bench before painting.
To build the table top, cut five one-by-six uniform boards a wood planer, arrange the boards over a flat surface, and stick the edges together with wood glue. Smooth the table top with sandpaper once the glue is dry.
To build the legs, cut four two-by-four boards to a suitable size with a table saw, and sand them. Attach the legs to a sawhorse bracket with wood screws. To make the lateral support board, cut four other two-by-four boards so that their length is slightly shorter than the table's width. Sand them, stick them together in pairs with wood glue, and allow the glue to dry. Then, screw the table leg sets onto the ends, taking care to extend them into a triangular shape.
Once the woodwork is complete, sand it with a fine-grit sandpaper, apply primer, and allow the primer to dry before applying a coat of paint. Allow the coat to dry, and paint again. Finally, set the bench top over the support boards once the paint is dry, and use the table.