This is an animated video created by Jared Owen detailing the inner workings of the humble gumball machine. I thought the engineering of the coin mechanism was particularly clever. Of course you don't need a video to understand how a gumball machine works, it's pretty simple. You just stick your quarter in like so, turn the handle, and-- wait, why isn't it turning? "That was a nickel." Screw it, I didn't want that flavorless rockball anyways (I'm gonna smash the glass with a hammer!).
Keep going for the video.
Thanks to Harry T, who agrees a handful of Runts > gumball any day.