Make and attach the frame. Measure and cut three 12-foot-long framing pieces and two 5-foot-6-inch-long framing pieces. Lay each piece on the ground. Sit each piece upright on its side and fit the frame together into a 12-foot-by-5-foot-by-6-inch rectangle. Power drill two screws to secure each corner. The 5-foot-6-inch pieces are inserted between the left and right frames at the top and bottom. The third 12-foot piece is positioned in the middle of the frame for additional support.
Make and attach the insert braces. Measure and cut 12 insert braces, measuring 2 inches by 6 inches. Measure each brace to 2 feet by 9 inches long. Each 2-foot-9-inch piece will sit upright on its side and fit flush in between the frames. Distance each brace apart by 18 inches in between both side and center 12-foot-long pieces--six braces on one side and six braces on another.
Measure and cut a 12-foot-4-inch-by-6-foot plywood floor panel. Place the panel on top of the wood frame. Power drill wood screws down into the panel, securing it to the frame. Attach a wood screw every 12 inches around the perimeter and down the center along the center frame beam.
Scrub the panel floor with bleach in a well-ventilated area. Bleach will remove plywood stains. Allow 24 hours for the plywood to dry. Paint the stage with a dark latex enamel and allow another 24 hours to dry before using it to perform.