Set the washtub, open side up, onto a piece of round plywood or a metal stand. The plywood option may be good if you can't find a metal stand to fit the tub or you don't want to spend as much. The washtub just needs something stable to sit on.
Add decorations to the inside of the washtub. If it's the holiday season, consider filling the tub with greenery and ornaments. For a springtime look, fill the tub about halfway with some water and float flowers. Alter the decorations according to the seasons to customize the table.
Place the glass tabletop on top of the washtub. The glass tabletop will serve as the top of the coffee table, and you will be able to clearly see what embellishments you have placed inside. It is also easy to remove when you want to change the décor of the coffee table.