Lenses, for example, focus light by allowing it to pass through different thicknesses, thereby slowing it down by differing amounts.

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Timberland asked for samples of 40 colors in four thicknesses.

FORBES: Entrepreneurs

This method allows better control of the thicknesses of the silicon and glass layers, but the etching is time-consuming and requires the costly sacrifice of a wafer for each one that is made.

ECONOMIST: Chip technology

They said that by using stereolithography, their printer could offer "layer thicknesses and feature sizes that are worlds ahead of what is possible with" the existing technique used by budget printers, which melt plastic and squeeze it through a nozzle to build up each layer of an object.

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