This clock, made by Greg Blonder from a Lego Mindstorms set, is an homage to the slide rule. It's super simple to read; the upper rule tells the hours and the lower tells the minutes. They move independently, and the stationary window shows the time. This update to a retro gadget is kind of hypnotizing to watch, even if it takes up about a foot of shelf space. As much as we like this, we're wondering when Greg will come out with an abacus Lego clock.