Open Source Microsoft 3D Builder Alternatives

Blender is the free and open-source 3D creation suite. It supports the entirety of the 3D pipeline—modeling, rigging, animation, simulation, rendering, compositing, video editing, and motion tracking.

FreeCAD is a general purpose parametric 3D CAD modeler. The development is completely Open Source (LGPL License).

LibreCAD (originally QCad then CADuntu) is an open source 2D CAD application for Windows, Apple and Linux. It is based on Qt, which is a leading cross-platform application and UI development framework.

OpenSCAD is a software for creating solid 3D CAD objects. It is free software and available for Linux/UNIX, MS Windows and MacOS.

Cura aims to be a end solution for personal 3D printing with RepRap based machines. It is tuned toward the Ultimaker, but can be used on any RepRap based design.

Bforartists is a complete 3D suite to create 3D content. It offers you the full 3D art pipeline to create game graphics, prerendered movies and stills.

BRL-CAD is a powerful cross-platform open source solid modeling system that includes interactive geometry editing, high-performance ray-tracing for rendering and geometric analysis, image and signal-processing tools, a system performance analysis benchmark suite, libraries for...

System for processing and editing 3D triangular meshes, provides a set of tools for editing, cleaning, healing, inspecting, rendering, texturing and converting meshes.

STL-to-GCODE translator for RepRap printers.

MatterControl is a free, open source app that lets you organize and manage your 3D prints. It's designed to help you get the most out of your 3D printer - making it easy to track, preview, and print your 3D parts.