Select a halogen work light with a 6-by-8-inch rectangle lens and a 500-watt halogen bulb. The lights come with a built-in pipe support frame with a handle. Release the adjustment lock by twisting and rock the light back, so that the face is pointing up.
Cut the corners out of a rectangle galvanized ventilation floor register duct box, with a 6-inch round inlet on the back. Use tin snips to cut along the fold of the corners from the front edge back to where the fold ends.
Fit the face of the light into the rectangle of the vent flange. Fold the cut flaps of the flange in around the light, on all four sides. Fold the corners in to create a snug box. Wrap chrome high heat duct tape around the edges of the flange to attach it to the light.
Mount the spot light to your light pipe overhead with a strap type hardware clamp, like those used to attach automotive hoses. Most light pipes, known as battens, are made from 1 1/2- to 2-inch pipes and the frame of your light will be 1/2 inch. Use two clamps and tighten them with a screwdriver or pliers.
Plug the light directly into a stage light dimmer, or use an extension cord to plug it into one for dimming and power control. Set the switch on the light to the "on" position.