BRL-CAD is an open source software package for 3D Computer Aided Design (CAD) and solid modeling, developed and maintained by the U.S. Army Research Laboratory (ARL). It is a powerful and comprehensive tool for creating and manipulating 3D models, and is used in a variety of fields including mechanical, aerospace, weapons, and biomedical engineering. With BRL-CAD, users can create and edit 3D models, analyze them, and produce high-quality 2D representations. It also provides powerful tools for simulating the behavior of objects under various conditions, including stress and strain, temperature, and other environmental factors. BRL-CAD is highly customizable and supports a wide range of file formats, including the popular STL and IGES formats. It is available as a free download, making it an excellent choice for professionals and hobbyists alike.
BRl is a complete package and Autodesk Free has a 30-day free trial period only.