SolidGeometryLib - this is Unity port of sgCore - https://www.geometros.com/index.html - solid modelling library for C++, C#, Objective-C developers under Windows, MacOS and iOS platforms. Designed for engineers and programmers dealing with 3D modeling, sgCore meets the majority of requirements in this field and provides high accuracy and modeling speed.

SolidGeometryLib library is developed by a group of highly-qualified programmers with a profound solid-state modeling experience. The API simplicity, a great number of functions and classes to create most complicated objects and manipulate them, the small size of the library itself, the full documentation and the 24-hour technical support.

Examples of usage: https://www.geometros.com/tutorials.html