Materials:old window
1x8 poplar lumber
circular saw
jigsaw
speed square
tape measure
drill
screws (1/2" and 2")
wood glue
1/8" luan plywood
pencil
1-1/4" finish nails
hammer
flush spackling compound
piano hinge
Steps:
1. Measure the length and width of the window and use those measurements to cut the sides, top and bottom of the cabinet from poplar using a circular saw and a speed square.
2. Place the boards on a flat surface and arrange them the way they will be assembled to form the cabinet. Drill pilot holes into the top and bottom pieces, and then use a countersink bit so two-inch screws will be hidden below the surface of the board. Use screws and glue to secure the pieces, which add more strength than nails.
3. Measure the inside of the cabinet for the shelves and cut them to length using the circular saw. Place the shelves inside the cabinet and make sure they're square. Drill pilot and countersink holes and attach the shelves with glue and two-inch screws as above.
4. To make the back, draw the measurements of the finished cabinet onto a piece of luan plywood, and cut it out using a circular saw or jigsaw. Attach it to the back of the cabinet using wood glue and finish nails. Fill all the screw holes with flush spackling compound and let dry.
5. Prime and paint the piece as desired and let dry.
6. Attach a piano hinge along the inside of the cabinet and the inside of the window with 1/2-inch screws.