Materials:piano hinge
safety hinge
1/8"-thick birch plywood
3/4" birch plywood
jigsaw
2x2 lumber
nail gun
circular saw
clamps
scribe
2" foam
fabric
staple gun
stain
cotton batting
Steps:
1. Clamp two pieces of 3/4-inch plywood together and draw the desired front curve onto the top one. Use a jigsaw to cut the curved front portion on both and to remove the center section of the top piece.
2. Cut a series of 2x2 braces to create the support structure for the bench base and secure them into position in each corner and along the front edge of the two plywood pieces using nails.
3. Cut 3/4-inch plywood to size for the side pieces and backing, and then nail them into position.
4. Hold the thin birch plywood in position along the front of the bench and use a pencil to mark along the top for the necessary width. Cut the piece to size using a circular saw. Lay the bench on its back and place the curved front piece in position. Starting at one end, nail along the edges using wire brads. As you get close to the opposite end, use clamps to hold it in place and more wire brads to secure it.
5. For the bench top, place the bench on top of another piece of 3/4-inch plywood and the trace along the piece using a scribe so the top piece is 1/2 inch longer and wider for a reveal.
6. Stain the bench and top as desired and let dry. To upholster the top, cover it with foam cut to the same size; cover it with batting, and then staple fabric over it.
7. Attach the top to the bench using a piano hinge and add a safety hinge to hold it up until you're ready to close it.