FreeCAD

FreeCAD is a free, open-source parametric 3D CAD and BIM modeler for mechanical engineering, product design, and architecture.

FreeCAD is a powerful, multi-platform (Windows, macOS, Linux) parametric 3D CAD application built on a modular, workbench-based architecture. This open-source tool (LGPL-2.0-or-later) excels in mechanical engineering and product design, but also supports Building Information Modeling (BIM) and Finite Element Method (FEM) analysis. Its core uses the Open CASCADE Technology geometry kernel, ensuring designs are fully parametric and easily modifiable via the model history. Users can extend functionality with Python scripting and seamlessly integrate it into workflows by supporting key formats like STEP, IGES, STL, and DXF for 3D printing and CNC machining.

https://www.freecad.org