His idea works on a similar principle to a solar chimney, which consists of a tall, hollow cylinder surrounded by a large greenhouse.

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The government may simply insist that 3D printer manufacturers install software that prevents printing of a hollow cylinder of a certain size, a firing pin, or a certain type of spring.

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Its design uses a hollow, buoyant cylinder that extends down from the tower to about 100 metres underwater.

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Over the next five years, the team will use a long, hollow, rotating drill to cut and retrieve a cylinder of ice roughly 12 centimetres across.

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