Here's a great paper automaton available for free from Pino at paperpino.net. Turn the hand crank to make the cams rise and fall. The cams in turn, shift up and down allowing the reels to 'climb' the moving stairs. When the reels reach the top, they spin down the curved ramp to start the process over again. And it's all made with paper and glue! Ingenious.
Here's where you can download the plans for The Rolling Reels Circus automaton.
[ Thanks Ian! ]