Sofas are expensive pieces of furniture and round sofas are no exception to this rule. A round sofa is a good looking and modern piece of furniture that will liven up any home, however. Round sofas look like oversized chairs and as such can be comfortably enjoyed by one or two people at a time. You can build a round sofa yourself to modernize your lounge without spending excessive amounts of money.
Building the Sofa Frame
Cut two sheets of ¾-inch-thick plywood with a circular saw to 3 1/2 feet long and 3 1/2 feet wide. Cut eight pieces of 2-by-4 to 10 inches long. Cut one sheet of ¾-inch-thick plywood to 11 feet long by 11 1/2 inches wide.
Draw a circle with a diameter of 3 1/2 feet on each 3 1/2 foot square plywood sheet, using a compass and pencil. Cut along the pencil lines on both sheets using a hacksaw or reciprocating saw, to produce two circular pieces of plywood. Lay one circle flat on the ground. Stand the eight 2-by-4 pieces on the circle so they stand at the compass points reaching 10 inches up from the ground.
Mark the position of each 2-by-4 piece with a pencil. Screw the 2-by-4 pieces to the circle using a hammer drill with screwdriver drill bit to countersink one long screw in each joint. Screw the other circle to the other end of the 2-by-4 pieces with countersunk 1-inch-long screws to form the round base of the sofa.
Cut one sheet of ¾-inch-thick plywood with a circular saw to 3 1/2 feet long and 1 3/4 feet wide. Cut four pieces of 2-by-4 to 11 inches long. Cut one sheet of ¾-inch-thick plywood to 5 1/2 feet long by 11 3/4 inches wide. Cut one sheet of ¾-inch-thick plywood to 4 foot 8 1/2 inches long and 11 3/4 inches wide.
Draw a semi-circle with a diameter of 3 1/2 feet on the 3 ½-by-1 3/4 sheet using a pencil and compass. Draw a second semi-circle with a diameter of 3 feet on the same side of the sheet. Cut along both pencil lines using a hacksaw or reciprocating saw to produce a 6-inch-wide curve of plywood.
Screw a of 2-by-4 piece 1 inch from each end of the curve at right angles to the curve using countersunk 1-inch screws. Screw the other two 2-by-4 pieces to the curve equidistant to the end 2-by-4 pieces, in the same manner.
Screw the other end of the 2-by-4 pieces to the edge of one of the circular plywood sheets using countersunk 1-inch screws. Cut two pieces of ¾-inch-thick plywood 11 3/4 inches long by 6 inches wide. Screw one piece to either end of the back support to cap off the support.
Make a ½-inch-deep and 11 ½-inch-long cut every 2 inches along the length of one side of the 11-by-11 ½-inch plywood sheet using a chop saw. Apply wood glue to each cut in the sheet. Bend the sheet around the sofa base so the cuts face into the base. Nail the sheet to the base using a hammer and 1-inch long nails.
Make a ½-inch-deep and 11 ¾-inch-long cut every 2 inches along the length of one side of the 4-foot-8 ½-inch-long plywood sheet using the chop saw. Apply wood glue to the cuts. Bend the sheet around the front curve of the back support with the cuts facing outward. Nail the plywood sheet to the back support via the plywood curve on the top and the four 2-by-4 supports.
Make a ½-inch-deep and 11 ¾-inch-long cut every 2 inches along the length of one side of the 5 ½-foot-long plywood sheet using the chop saw. Apply wood glue into each cut. Bend the sheet around the outer curve of the back support with the cuts facing into the support. Nail the sheet to the plywood curve on top of the back support and the 2-by-4 pieces inside.
Applying the Upholstery
Cut an 11-foot length of upholstery with scissors. Spray the spray mount all around the outside curve of the sofa. Roll the upholstery around the sofa so the two ends touch in the middle of the back of the sofa. Hold the upholstery in place while the spray mount dries, so the upholstery attaches to the plywood.
Cut a straight line from the top of the upholstery down to the top of the plywood seat on either side of the back rest. Cut along the top of the front seat to remove the excess upholstery. Apply spray mount to the bare plywood on the top and front of the back rest. Fold the spare upholstery onto the back rest, cutting off any excess on either side. Hold the upholstery in place while the glue dries.
Draw a circle with diameter 3 1/2 feet on the back of a piece of upholstery. Cut the circle out. Apply spray mount to the bare plywood on the seat of the sofa. Place the circle of upholstery on the sofa seat and cut off the excess with scissors. Hold the upholstery in place until the glue dries.
Making the Cushions
Cut a piece of upholstery foam 3 1/2 feet long and 11 inches wide using a craft knife. Make a series of cuts three-fourths of the way through the foam every 2 inches along the length. Apply PVA glue into the cuts on the foam. Place the foam against the back rest on the sofa with the cuts facing outward. Hold the foam in place until the glue dries.
Draw a circle radius 3 1/2 feet on a piece of furniture foam. Cut this circle out using a craft knife. Remove the back support foam from the sofa. Place the circle on the sofa. Cut away the excess foam from the circle until the foam is in the shape of the seat.
Place the back support foam back on the sofa. Cut away the excess back support foam with a craft knife until the back support fits on the sofa with the seat foam already in place. Remove the back support foam from the sofa. Remove the seat foam from the sofa as well.
Wrap a length of upholstery around the back support foam and cut the upholstery at the point where the edges overlap on one-another. Sew one short side and one long side of the upholstery piece together using a sewing machine. Sew a long zipper into the remaining long side of the upholstery to form a cushion cover. Push the back support foam into the cover. Zip up the cover.
Draw a circle radius 4 feet on the back of a piece of upholstery. Cut the circle out. Draw another circle radius 3 1/2 feet on the back of a piece of upholstery. Cut the circle out. Place the 3 1/2 foot circle underneath the seat foam. Place the larger circle on top of the seat foam. Fold the fabric around the foam and cut it to the correct shape to cover the seat foam.
Sew the pieces of upholstery together using the sewing machine. Leave the back curve of the upholstery open. Sew a long zipper into the upholstery along the back curve to form the seat cushion cover. Push the seat foam into the cushion cover. Place the seat cushion on the sofa. Place the back support cushion on the sofa.