- 1 ping pong ball, halved
- 1 rubber band or plastic to hold halves about nose-width apart
- 1 Set headphones
- 1 recording of white noise
Just sit in a lit room with the ping pong balls and headphones in place and do...nothing for 10-30 minutes. See what happens.
Or you can read this research account. The hallucinations are widely reported and quite vivid. It is not news that sensory deprivation causes this; it is news that it is so easy to induce. There is no need for a deprivation tank, just a chair, a ball, and an iPod.