Measure the space so the lumber can be cut to the exact specifications needed for a banquette. Cut out a cardboard template that will show exactly where the banquette will fit into the room and also function as a stencil when you are ready to start sawing.
Cut out the round seating surface and straight-lined support frame sections of the banquette with a table saw, using the cardboard stencils as a guide for the rounded curvaure of the banquette's seating area. Wear protective goggles, and use caution when working with power tools.
Nail the banquette’s angular outer and curved inner frame segments together to set its structure. Reinforce the banquette by screwing the pieces together for a more permanent hold.
Set the straight-backed ends of your round banquette against the walls that you intend to attach the piece of furniture to. Bolt the linear ends to the walls using wood screws to ensure stability, with the rounded seating section facing outward.
Paint or stain the banquette’s outward facing sides to match the dining area.
Secure the banquette’s seating surface with wood screws along the edges and corners of its frame. Top off the round banquette with cushions and pillows.