The generic term 3D printing covers a wide variety of different technologies and materials, albeit with the common goal of producing three dimensional objects. In most cases these objects are created one layer at a time, with successive layers built on top of each other, often with a secondary material to support the object while it's being created. There are many different approaches, such as extruding plastic, heated to a near liquid form, which then hardens as it cools. An alternative is stereolithography, which essentially uses resins that can be cured by UV light to form plastic objects. There are also metal printers that lay down powdered metal, which is then fused into solid objects through the use of lasers.
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