Decide what size your case needs to be. Lay the guitar and all its parts, including the legs if you have them, out on the work bench. Measure the length, width and height needed. Add 4 inches to your length and width measurement and 2 inches to the height.
Set up your table saw. Cut two rectangles out of the 1/4-inch sheet of wood using your length and width measurements. Check that they are cut square with the T-square. Divide your height measurement in half and cut 8 strips of 1/2-inch pine using that measurement. Cut four of those pieces down to your length measurement. Take 1-inch off your height measurement and cut the last four pieces to that size. Sand all the wood with the sand paper.
Use two long and two short pieces of cut 1/2-inch pine to set up the frame of the case on the work bench. Have the 1/2-inch side facing the work bench. Place the two short pieces inside the two long pieces at each end. Square it up with the T-square.
Run a thin bead of glue along the top edge. Carefully place one of the 1/4-inch sheets on top lined up with the edges and nail it into position. Nail the edges together with the nail going through the long piece into the end of the short piece. Make a second unit with the remaining pieces.
Place one box on top of the other to form a closed box. Cut the piano hinge down to fit along one of the long edges. Screw the hinge into place with the center of the hinge running along the crack between the two sections.
Attach the two case closing clasps with the provided screws evenly spaced on the other long edge of the box. Screw the handle into position making sure you can still open and close the box.
Use a carpenter's knife to cut two pieces of memory foam to fit into each side of the open box. The foam should be the same thickness of the side of the box it's fitting in to. Remove the foam and spread some glue inside of the box to hold it in place and press the foam into position.
Place your guitar into position on the foam. Cut slots to hold your guitar picks. Close the case and leave it that way for a day. The foam will start to take shape around the parts. If you wish you can paint or stain the case.