Acquire a rigid urethane foam ball about 6 to 7 inches in diameter. Cut off the top of the ball about 1 inch down from the top. Save this “cap.”
Hollow out the ball using a spoon that has been sharpened on the edges on a grinder into a curved “scraper.” The walls of the ball should be 2 inches thick.
Drill “air holes” in the ball, about ½ inch in diameter, and in a random pattern. Make about one hole every 2 inches around the surface of the ball. The holes should go through the outer shell of the ball and into the hollow inside portion of the ball.
Drill a ½ inch diameter hole through the top of the ball, at the open end, so the hole goes all the way through the bottom of the ball. Drill a corresponding hole through the center of the cap.
Thread a large washer on an 8 inch long, ½ inch diameter carriage bolt. The washer should rest against the head of the bolt.
Insert this carriage bolt up through the hole in the bottom of the ball. Thread the cap onto this bolt. Press the cap down against the ball so it “seals” the ball closed, with about an inch of bolt sticking up out of the cap.
Drill a ¼ inch diameter hole through the protruding end of the bolt, about ¼ inch from the end of the bolt. Use a metal drill bit.
Install a very small carabiner through this hole in the bolt. You should be able to dangle the ball while holding the carabiner.
Remove the carabiner from the bolt, slide off the cap, and set both aside.
Cover the entire shell of the ball with tiny mirror tiles or beads. The mirrors should be no larger than ¼ inch square or ¼ inch in diameter. Use Goop Adhesive to affix the mirrors to the ball. Do not cover the “air holes” or the cap.
String two black cotton fishing lines between two points in the theatre. These lines should be set well above the heads of the audience. Run two lines, for example, from one balcony stage left (Point A), to another balcony stage right (Point B). One string forms the “track.” The other string forms the “pull line.” Do not use clear fishing line: it reflects light too much.
Replace the cap on the mirror ball bolt and reattach the carabiner to the bolt.
Thread the carabiner onto the track line and move the mirror ball along the track line back to Point A. Tie off the loose end of the track line to Point B. This now “closed” track line should be taut. The mirror ball should dangle down from the track line. If the ball causes the track line to sag too much, use a thicker black string line.
Tie the second string, the puller line, to the carabiner. Deliver the free end of the puller line to Point B. Standing at Point B, reel in the puller line; the mirror ball will travel down the track line from Point A to Point B. Do this very fast by hand or rig a reel.
Lift the cap and load the inside of the mirror ball with chunks of dry ice. Use tongs to load the ice. The ice will immediately begin to produce fog which will stream out of the air holes in the mirror ball. You can accelerate this effect by spritzing warm water on the ice.
Clamp the cap down on the mirror ball. Seal it with a piece of clear tape.
Practice “flying” the ball from Point A to Point B. Play with speed of the travel. You can make the ball “bob” up and down by manipulating the track line.
Place a “douser bag” at Point B. The douser bag should be made of black velvet, large enough to hide the ball when the effect is complete at Point B.
Turn off the theatre lights. Run the mirror ball along the track, streaming dry ice fog as it goes. Shoot the ball with two powerful pinpoint spot lights as it travels the track. The trick is to rehearse the effect until the entire Effects team is perfectly orchestrated. The trick will take five to six technicians’ efforts, and will last only three or four seconds, but the effect will be spectacular.
Add diversionary effects by firing strobes and other lightning effects on stage. The audience will be so caught off guard by the “flash bangs” they will hardly have time to figure out where the ball lightning came from.