I SMed Pippin a couple years ago. For the firebox we had a very creative volunteer build a box about three feet square, 8 feet tall. A plastic Halloween skeleton was hanging from the top center, behind a piece of black fabric, also hanging from a small piece of wood. The wood, fabric and skeleton could all be rotated quickly, probably a lever on the side of the box. There were light ropes inside the box, and on top was a small tube. The tube was filled with flour? Talcum? something powdery. The other end of the tube was hooked to an air compressor and charged up before the show. The leading player could then hit the power button for the lights and the air compressor, which resulted in a bright-ish flash of light with a nice mushroom cloud of smoke. Another assistant at the same time would pull the lever, so it looked pretty much like a flash of flame, a fireball and poof a skeleton appeared. I wish I had photos or a video to share. All in all, it worked pretty well, except the time I accidentally triggered the mushroom cloud about 15 minutes before the show started.