We are making a kaleidoscope for Burning Man 2001.
It will be 8 feet long with a 10" per side triangle, standing on a 4 foot tall base (see pics below). The structure is a truss John found almost exactly one year ago. The mirrors will be made of reflective acrylic. There will be spinnable acrylic discs at the end filled with cool things (beach glass suspending in liquid, colored oil?). People can draw their own discs as well.
Update 8/14: We shipped the kaleidoscope last weekend! It took a ridiculous number of hours to finish, but we did it! Now to do the visuals and the electricals!
Kaleidoscopes by John Hoag (Howto)
World's Largest Kaleidoscope (ours is the world's larget portable kaleidoscope)