To build a deck bench, you'll first need to gather your tools such as circular saw, hammer, varnish, stain, power drill, and wood bit, as well as your screws. Next, you'll need to make the frame. You may use existing deck material to make your bench. Then decide whether you want your bench to sit against the wall or on all four legs. If you choose the latter option, make the legs and screw them onto the frame.
Finally, cut leg bases, bolt them to the center of legs, and lag bolts. Then round outer edges and ends of seat boards, using a router. Finally, attach three seat boards to the frame and paint or stain according to personal preference.