STL Files
STL is short for STereoLithography or Standard Triangulation Language. This language views any object as a collection of surfaces, and describes each surface of the object as a collection of triangles.
For example, a square can be described as two triangles; a cube (six squares) as 12 triangles. Curved surfaces need more triangles to describe them. The higher the tolerance (for smooth surfaces), the more triangles are needed.
Most CAD software can export STL files.
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