Use a 5 gallon bucket to trace two circles on 3/4 inch-thick medium density fiberboard (MDF). The circles should be 16 inches across. Cut the circles out using a jig saw. Glue and nail the circles together to create a base. Drill a hole through the center of this base with a 1/2 inch paddle bit. Mark a 1/2-inch wide strip from the hole to the edge of the base on the bottom, using a square. Chisel the material from this strip to a depth of 3/8 inch.
Cut a piece of 3-inch diameter galvanized conduit or fence post pipe to the height you want your light post to be, using a hacksaw. Attach a 3-inch threaded pipe floor flange to the top of the MDF base, using a 1 1/4-inch treated deck screw through each hole in the flange. Center the flange on the 1/2-inch hole you drilled.
Use wire cutters to cut the female end from a heavy duty extension cord. Cut the outside case from the cord with a utility knife about 2 inches back from the end of the cord. Use a wire stripper to strip the insulation from each of the three wires in the cord. Fit each wire in the strippers and close the pliers firmly. Pull the stripper toward the end of the wire to remove the insulation.
Run the cord up through the hole in the base and thread it through the pipe. Select a lamp head designed for a 3-inch post. Pull the ends of the insulation from the wire, which are typically precut. If not, strip the wires back 1 inch.
Thread a wire nut to each pair of color coded wires on the cord end and the bottom of the light fixture. Tuck the wiring back into the top of the pipe. Fit the bottom of the pipe into the floor flange on the base and tap it home with a rubber mallet so that it is firmly seated in the flange.
Fit the cap of the light base onto the pipe and tighten mounting screws around its edge to attach it to the pipe. Tuck the cord wire into the 1/2-inch wide groove you made in the bottom of the base, then cover it with a strip of black cloth duct tape to hold it in place.
Coat the pipe and base with a color of spray paint that match the lamp. Hold the can 8 to 10 inches from the surface. Spray the paint on with short bursts, in brush-like motions. Work in overlapping strokes to ensure proper coverage.
Plug the cord into a standard outlet, or into a stage light dimmer outlet so that the lamp can be controlled remotely.