"Svengali pads," are magic props that, like a Svengali deck of cards, selectively shaves down alternating leaves so that a performer can seemingly riffle all the pages but only display every second page.
There are a lot of effects you can produce with a Svengali pad — riffle the pages one way and they're all blank, riffle them another and they are written-upon, spelling out a message; or show a series of black and white line-drawings, do something magical, and riffle them again to show that they're all in color, you get the idea.
Commercial pads are $25, but you can make your own, virtually for free (the pads will cost you $0.88 for a four-pack). As Andy at The Jerx writes, most print shops will happily guillotine the edge off a pad at an angle, and then you can carefully unwind the coil holding the pad together and interleave the gimmicked pages with ones from an unaltered pad, and reaffix the coil, producing your own magic pad for pennies.
Tina S.: "Even the pros might be content with the homemade ones. Especially when you consider the commercially available ones are $25 a piece and you can make your own in about 12 minutes for, literally, 22 cents (the notebooks were sold in a 4-pack for 88 cents) plus whatever you want to give the print shop for chopping off the bottom of the pad. They don't generally have a set price for such a thing. The professionally made ones might be twice as good, but they're not an order of magnitude better."Trent: "You might think the pages would shift around with the thin wire going through larger holes which would affect the riffling of the pages. But it doesn't. There's a lot of friction between pages. We tried to get the pages to shift around or to make the gimmick not work and we couldn't."
