Measure the spaces in the bookcase where you will fit each drawer. Take each measurement twice to ensure accuracy. Hold the measuring tape exactly at the edge of each surface when measuring. Calculate the size for each drawer by subtracting the space required for the runners from the space of the bookcase.
Use a hand saw to cut all lumber to the prescribed dimensions. Have a local hardware shop or lumber supply store cut the pieces for you if you are unskilled at making cuts to precise measurements.
Use a circular saw to cut a lengthwise groove 1/4 inch from the bottom edge of the two boards that form the sides of each drawer. Arrange the side pieces so they form right angles with the board that forms the back of the drawer and the grooves face inward. Apply glue to the edges of the side pieces and hold them securely against the back piece. Screw the pieces together. Use a T-square to keep the angles at 90 degrees.
Apply glue to the exposed edges of the side pieces. Set the front piece of the drawer in place, using a T-square for right angles. Screw the piece in place. Follow the manufacturer's instructions to let the glue completely dry.
Attach the drawer runner hardware to the sides of the drawer and the inside of the shelving unit. Follow all manufacturer's instructions, using the indicated screws or nails. Take all measurements twice before affixing the hardware.
Measure the front of the drawer to determine its center. Mark the spot with a pencil. Screw your drawer pull hardware so it is centered around the spot.
Sand the entire drawer, inside and out. Start with rougher sandpaper and finish with finer gauge paper. Wet the fine sandpaper for a final sanding.