Gurrufío

The Gurrufío is a simply constructed traditional children’s toy, very popular in Venezuela. It is made from a soft drink bottle cap that has been hammered flat, with holes drilled or nailed equidistant and close to the center. A rope is inserted through both holes, leaving a length of about 15 to 30 centimeters on each side, and the loop is closed with a knot.

Take the ends of the loop at both sides with the fingers, rotate the disk a bit, and draw the rope taut, fast, and release the tension a bit. The disk will spin in one direction, reach its maximum, and then, helped by another yank, start spinning in the opposite direction.

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Wikipedia