One of my favorite exhibits at Maker Faire Bay Area 2013 (held last weekend) was Alex Andre's Metamorphosis Project. It's a six-foot-diameter spinning disc with a hand crank. The disc is made of clear glass and mirrors in alternating quadrants. You stand on one side and line up your nose with a person standing on the other side. As the disc spins, you see a rapidly flickering image of your reflection and the other person's face. The effect was hallucinatory - I not only saw my face merge with the other person's face, but I also saw faces pop in and out that looked nothing like either of our faces. These videos give you just a small taste of the trippiness. I hope you get a chance to experience it yourself one day.
Mark Frauenfelder is the founder of Boing Boing and the editor-in-chief of MAKE and Cool Tools. Twitter: @frauenfelder. His new book is Maker Dad: Lunch Box Guitars, Antigravity Jars, and 22 Other Incredibly Cool Father-Daughter DIY Projects