Purchase a large panel of 3/4-inch-thick wood. It can be any type of wood. Hardwood is best if you intend to leave a natural finish. Plywood is best if you want to paint your table.
Use the jig saw to cut the 3/4-inch wood panel into an oval. Drawing a large rectangle and rounding the edges is the easiest way to do this.
Use the jig saw to cut the 4-by-4-inch lumber into four legs. Make them as tall as you want the table to sit.
Cut the 6-by-1-inch lumber into four square panels that measure 6 inches in length and width. These will serve to connect the legs to the table. Use wood glue and screws to secure each 6-by-6 panel to the top of each leg.
Put the tabletop upside down on a clean surface. Slightly in from each corner, attach the legs to the table. Use wood glue on the 6-by-6-inch panels attached to the top of the legs and secure them to the underside of the table, using screws.
Stand the table right side up. Use the level to ensure the table is straight.
Sand the entire table, including the legs.
Apply a coat of varnish, and allow to dry according to the instructions on the package.
Add another coat of varnish, making sure to concentrate on the table top, as that is the area that will receive the most damage and wear.