Create the framework of the seat by cutting two 2x4s to 18 1/2 inches in length, and cutting another two to 14 1/2 inches in length. Screw brackets into the frame pieces and secure them together, making a box shape.
Top the framework with plywood cut to 18 1/2 x 14 1/2 inches. Run wood glue around the top of the frame and lay the plywood on top. Drill down through the plywood and into the frame to secure the top to the frame.
Purchase table legs, bench legs or cut legs from 2x4s to 17 1/2 inches in height. Locate one leg in each corner of the frame and secure into place using a metal device known as installation hardware for table legs. Screw this metal plate to the table leg and then to the plywood in each corner.
Cut a brace piece that fits snugly against the table leg and each side of the frame. Use a miter box to cut a 45 degree angle to make the brace fit up to the frame. The brace will make a triangle with the table leg inside. Screw the brace to the frame to add stability to the table leg and prevent wobbly legs.
Add any embellishments you care to such as scroll work. Sand the dressing table bench and clean it using a tack cloth. Apply a paint of coat or stain to the bench and allow it dry thoroughly.
Sew a one inch seam all the way around your upholstery fabric. Be sure to leave both ends open, do not sew it shut.
Pin your safety pin to one end of the elastic band and thread it through your seam. Leave the ends of the elastic exposed.
Spray the top of the dressing table bench with spray tack. Lay the upholstery foam on top of the dressing bench and press firmly into place. Allow to dry thoroughly.
Lay your upholstery fabric over the plywood and pull the elastic strings together to secure the fabric over the upholstery foam. Tie the two ends together and tuck up under the fabric. Don't sew it, leave it tied so you can remove the upholstery for laundering.