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.)

Amazon's Under-the-Radar Coupon Page Features Deals on Home Goods, Electronics, and Groceries

Stock Catalog, Flickr // CC BY 2.0
Stock Catalog, Flickr // CC BY 2.0

This article contains affiliate links to products selected by our editors. Mental Floss may receive a commission for purchases made through these links.

Now that Prime Day is over, and with Black Friday and Cyber Monday still a few weeks away, online deals may seem harder to come by. And while it can be a hassle to scour the internet for promo codes, buy-one-get-one deals, and flash sales, Amazon actually has an extensive coupon page you might not know about that features deals to look through every day.

As pointed out by People, the coupon page breaks deals down by categories, like electronics, home & kitchen, and groceries (the coupons even work with SNAP benefits). Since most of the deals revolve around the essentials, it's easy to stock up on items like Cottonelle toilet paper, Tide Pods, Cascade dishwasher detergent, and a 50 pack of surgical masks whenever you're running low.

But the low prices don't just stop at necessities. If you’re looking for the best deal on headphones, all you have to do is go to the electronics coupon page and it will bring up a deal on these COWIN E7 PRO noise-canceling headphones, which are now $80, thanks to a $10 coupon you could have missed.

Alternatively, if you are looking for deals on specific brands, you can search for their coupons from the page. So if you've had your eye on the Homall S-Racer gaming chair, you’ll find there's currently a coupon that saves you 5 percent, thanks to a simple search.

To discover all the deals you have been missing out on, head over to the Amazon Coupons page.

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What Is the Electoral College?

YouTube // CGP Grey
YouTube // CGP Grey

The Electoral College is a process used in the United States to elect our president. It was established in Article II of the U.S. Constitution.

It was created to address a series of technical and political problems that were present in the early days of our democracy—most notably, the issues of slow communications (it took tremendous time and effort to get vote tallies back to Washington from distant states) and of suffrage (the idea of a pure popular vote was a hard sell when you had Southern states containing large populations of enslaved African Americans and unenfranchised women). But we've been doing this national election thing for a couple hundred years, the suffrage issue is sorted out, and we have good telecommunications—so why do we still have the Electoral College? In a word: Federalism. In a few more words: The framers of our Constitution deliberately set up an indirect democracy.

There are lots of interesting arguments for and against the system. In the below video, YouTube educator C.G.P. Grey explains the issues inherent in the Electoral College. Take a look, and consider the question: Is this system really fair?