Watch This "Impossible Object" Dovetail Cube Puzzle

Kenjamoto // CC BY 3.0
Kenjamoto // CC BY 3.0

This puzzle is devious. Externally, it looks like a cube with dovetails cut on four sides—which should be impossible. Dovetail joints are normally cut to join two planes to each other, like the front of a drawer with its side. It shouldn't be possible to cut dovetails across four interlocking how does this puzzle do it?

You can just skip ahead to the video below if you'd like a visual explanation—or I'll spoil it for you now. In short, the "impossible dovetail" relies on a hidden set of diagonal cuts that allow the puzzle to slide apart diagonally. There's often a pin or other fastening mechanism to prevent an accidental slide, making the joints appear firm and fast until you press it.

The logic of this puzzle plays on our assumptions about how dovetail joints work. Because these joints typically prevent motion in two planes, those are the planes we look at. Is it possible to pull the top off the puzzle? Nope! How about side-to-side? Impossible! By adding a dimension to the puzzle, the solution is revealed in that extra dimension as well—you've got to slide the pieces apart diagonally. The joints, of course, aren't's our assumptions about how dovetail joints are cut that are incorrect.

In this video, "Mr. Puzzle" walks us through the solution to a wooden version of the puzzle (the solution starts at 1:52). Have a look:

If you're curious how this thing was made, here's a similar project by Clickspring, but machined out of aluminum. Behold:

If you'd like to make your own puzzle, free plans are online for a wooden version (requires a hand saw, coping saw, and chisel) as well as a plastic version (requires 3D printer).

(Image by Kenjamoto // CC BY 3.0.)

Watch 25 Minutes of Friends Bloopers Ahead of HBO Max Reunion Special

Jennifer Aniston, Matthew Perry, and Courteney Cox star in Friends.
Jennifer Aniston, Matthew Perry, and Courteney Cox star in Friends.
Hulton Archive/Getty Images

Much like The Office, Friends continues to enjoy an always-growing and ever-loyal following—thanks in large part to streaming services, but also because of its brilliant cast and still-relatable storylines. And now that all six cast members have officially confirmed they'll be returning for a reunion show on HBO Max, could fans of the series be more excited?

Though very few details have been offered up about the reunion, it's expected to be an hour-long special that will bring Jennifer Aniston, Courteney Cox, Lisa Kudrow, Matt LeBlanc, Matthew Perry, and David Schwimmer back together again. In addition to the special, subscribers to HBO Max will have access to all of Friends's 200-plus hilarious episodes.

So in the spirit of warming up for what will inevitably turn into a Friends marathon, here are 25 minutes of bloopers, in two parts, for your enjoyment.

The Friends reunion special does not have a release date yet, but HBO Max is debuting in May 2020.

23 Weird Laws You Might Have Broken

Mental Floss editor-in-chief Erin McCarthy hosts "The List Show."
Mental Floss editor-in-chief Erin McCarthy hosts "The List Show."
Mental Floss via YouTube

If you've ever played a game of bingo in North Carolina, you may have been a party to a crime without even knowing it. And if you've ever eavesdropped on a neighbor in Oklahoma and shared any of that juicy gossip, you might just want to go ahead and turn yourself into the police.

From coast to coast, America is full of bizarre laws that you've probably broken at one time or another. Join Mental Floss editor-in-chief Erin McCarthy as she digs into the history of 23 of the strangest of them—like why you can't eat fried chicken with a knife and fork in Gainesville, Georgia. You can watch the full episode below.

For more episodes like this one, be sure to subscribe here!