Steps:1. Measure the opening and decide on a design.
2. To add a bit of detail, make a frame of 1x4s (top and bottom rail, and three or four verticals for structure). Apply a piece of 1/4-inch plywood to the back of the frame, which will be the inside of the seat (figure A). Cut the 1x4 with the power miter saw, the plywood with the table saw and assemble it all with the pneumatic nail gun.
3. Cut a notch at each end of the panel you just built to match the profile of the baseboard molding in the room. Use the profile gauge to get the proper shape. Notching the window seat instead of removing the baseboard will leave the house intact if you should ever want to remove the seat.
4 Install the front panel by attaching two cleats made from 1x4 to the side walls (figure B). Measure 18 inches out from the wall and attach the cleat. Nail the front panel to these cleats.
5. The top of the bench will be made from 3/4-inch birch plywood. Cut the plywood to 19-1/2 inches using the table saw. Cut two openings in the plywood with a jigsaw to serve as doors to the storage compartment (figure C).
6. Screw piano hinges to the seat frame and the storage compartment doors.
7. Melt the edge-banding onto the front edge of the seat using a regular clothes iron.
8 Install a 1x2 cleat to the back wall, at the same level as the top of the front panel. Once the cleat is screwed to the wall, nail the top seat down to the cleat then to the front panel.
9 Fill any nail holes with filler and caulk the corners with painter's caulk. Prime, paint and you're ready to have a seat.