Open the hinged flip-top table on the sewing table. Remove the sewing machine by unplugging the cords from the machine. Turn the sewing table upside down. All sewing tables will have a shelf, carriage or brackets underneath the tabletop. These components are what hold the sewing machine in place while stored under the tabletop or in an upright position for sewing. Use a screwdriver to remove the hardware that is holding these components in place.
Measure the dimensions of the hole in the tabletop. This is how big the opening will be for your soil box. Add 2 inches to the width and length measurements. Use a jigsaw to cut two pieces from a 1-by-6 board using the length measurement. Cut two pieces from a 1-by-6 board using the width measurement, plus 1 inch.
Stand each of the boards on a long side and form into a rectangle. Place the ends of the width boards over the ends of the length boards. Attach the corners. Drill two pilot holes through the outer side of a width board end and into the cut ends of a length board. Insert 2-inch wood screws into the pilot holes and attach. Repeat on the remaining corners. This is your box frame.
Place the box frame on a scrap of 1/4-inch-thick plywood. Trace around the outside of the frame using a pencil. Cut the traced shape using a jigsaw. This is the bottom of your box.
Place the cut plywood on the frame and align the edges. Attach the bottom to the frame. Space pilot holes approximately 2 inches apart, through the plywood bottom and into the frame. Insert 2-inch wood screws into the pilot holes and attach.
Stand the sewing table right side up. Hold the box under the tabletop and align with the table's hole. Use a brace or the help of a friend to hold the box in place. Space pilot holes approximately 2 inches apart, through the tabletop and into the frame of the box. Insert 2-inch wood screws into the pilot holes and attach.
Attach cup hooks into the front edge of the sewing table. Hang hand gardening tools from the hooks. Place seeds and other small potting supplies in the drawers.