When you lay an old door flat, it provides as much usable space as a good-sized dining room table, although it's a little narrower. While a door probably wouldn't make a good dining room table indoors, it makes a perfectly serviceable outdoor table for picnics, drink service and more. All you need to turn a door into an outdoor table is a base, and this doesn't have to be elaborate. You can make a simple one with two-by-four lumber. If you'd rather not handle a power saw, you can complete this project without one, but you do need a drill.
Measure the length of the door with a tape measure, and cut two pieces of two-by-four lumber that are about 4 inches shorter. Use a circular saw to cut the lumber if you're comfortable with one; otherwise, use a handsaw. When you're done, measure the width of the door; cut two more pieces of lumber that are 7 inches shorter.
Assemble the four pieces of lumber into a frame on a flat surface. The wood should be standing on its edge, not flat on the ground. Put the shorter pieces between the longer ones to make a rectangle.
Drill two 1/4-inch holes through both ends of each of the longer pieces and into the ends of the shorter ones. Drive a 2 1/2-inch screw into each hole with a No. 2 Phillips bit.
Cut four lengths of two-by-four lumber for the table legs. They can be as long or short as you want, but the standard height for a table is about 32 inches. Fit one leg into each corner of the frame with one end on the ground, and screw it to the two intersecting edges of the frame with 2 1/2-inch screws. Don't forget to drill a 1/4-inch pilot hole for each screw.
Brace the legs with diagonal two-by-fours that extend from the middle of each leg to the frame. Each leg needs two of these to anchor it to the two parts of the frame to which it is attached. You can cut these without the need for any measurements.
Hold a two-by-four at an angle so it cuts across the outside face of one of the legs somewhere in the middle and the inside face of the frame about 12 inches from the leg. Draw lines on the two-by-four to mark the outside edge of the leg and the top of the frame. You'll have to lift the frame a little to do this. Cut the brace along the lines.
Hold the brace so that the cut lines intersect the edges of the frame and the leg, and screw it to the leg and frame with 2 1/2-inch screws.
Make another brace that intersects the perpendicular edge of the leg at the same point that the other brace intersects. It should intersect the perpendicular frame rail at a point 12 inches away. Mark the lines, cut the brace and attach it with 2 1/2-inch screws.
Make similar braces for the other three legs, and attach them in the same way.
Turn the frame over and screw two 1-inch metal corner brackets to each side of the frame. Set the door on the frame, center it and screw it to the metal brackets. Make sure you use screws that are short enough to sink into the door without coming through the other side.