Impossible Wallet

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From Amazon: BUY NOW Magic Wallet 
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Impossible Wallet: this pocketbook has a special double hinge that allows the wallet to be opened from either side, and leads to some rather nonintuitive consequences. Note that once inserted, the bill shows the same face independent of which way the wallet is opened. The construction of this magic (or flip) wallet is similar to the famous Jacob's Ladder toy.

Impossible Knot

Follow the link below for full explanation and instructions. 
From mathematician/artist George Hart: Tying the Knot Puzzle 

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Impossible Knot: how did this overhand knot get into this closed continuous band of rubber? It did not get there by cutting the loop, tying a knot, and rejoining it. Amazingly this band was once a rubber o-ring. How was it cut to produce a knot? An “impossible object” related to the Möbius strip by mathematician and artist George Hart- a brain teaser puzzle he calls “Tying the Knot”.