I first posted this inquiry in the "Coin Magic" section; I probably should have posted here, too.

In his "Expert Coin Magic" tapes, David Roth says that he designed his Okito slot box using an principle that had been around for a long time, but had never been applied to coins.

Just curious if anyone knows what he is referring to. I've read Professor Hoffman's MODERN MAGIC and LATER MAGIC, but didn't recall anything that would apply here. I'm familiar with a slot glass, but of course, that's a completely different principle and effect. SETH