No matter how you rotate a circle, it’s width will always stay the same. So far, so obvious. But if you thought this property was unique to circles, then these shapes of constant width will blow your mind. Check out the video to see them in action.

You can buy them with or without a pair of wooden rulers like in the video.

You'll also get a handy information sheet that tells you all about these unusual shapes.

They're available at different prices in wood, acrylic and card (click the smaller images to the left to see wood and card)

The acrylic shapes come with a protective plastic sheet to peel off, just like a new calculator. Mmm… new calculator.

£16.99 (p=266)