How to export STL
from Unity?

Unity is a game engine made by Unity Technologies. It supports more than 25 different platforms. This engine is used mostly to design three-dimensional, two-dimensional, virtual reality, and augmented reality games. It has been adopted not only by video gaming industry, but also by film, automotive, architecture, engineering and construction.

Unity enables users to develop games and experiences both in 2D and 3D, and offers a primary scripting API in C#, as well as drag and drop functionality. Within 2D games, Unity provides importation of sprites and a 2D world renderer. For 3D games, it allows specification of texture compression, mipmaps, and resolution settings for each platform it supports. Also, it provides support for bump mapping, reflection mapping, parallax mapping, screen space ambient occlusion, dynamic shadowing, render-to-texture and full-screen post-processing effects.

STL (STereoLithography) is a file format native to the stereolithography CAD software. This file format is supported by many other software packages; it is widely used for rapid prototyping, 3D printing and computer-aided manufacturing. STL files describe only the surface geometry of a three-dimensional object without any representation of color, texture or other common CAD model attributes. The STL format specifies both ASCII and binary representations. Binary files are more common, since they are more compact.