The ingenious perpetual flip calendar from the 1920s

This Perpetual Flip Calendar has a nifty way of displaying the date every time you rotate it 180 degrees. The Measured Workshop YouTube channel got the 1926 patent application and recreated one out of wood.

Here's a 3D printed version!

[via Core77]

Image: YouTube

from Boing Boing http://ift.tt/2HUVnSZ
via IFTTT

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