In 1991 a boss decreed that Gruber couldn't buy a machine called an extruder, which turns plastic pellets into clear film.

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The extruder is designed specifically for use with MakerBot PLA, a new plastic material based on corn, that Bre Pettis claims wont expand when exposed to the heat -- which means it wont contract when it cools, leading to smoother printed objects and less cracking.

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IBM's design involved feeding small plastic wafers into a heated pump that melted them and pushed the goo through an extruder.

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