Open source alternatives to CAD and simulation software include Blender, Bricad, and K3D, primarily available on Linux distributions. While there are several 2D CAD packages, their functionality is limited compared to commercial options like AutoCAD and SolidWorks. Users have found that open source solutions often fall short in handling complex projects, leading them to revert to professional software like Pro/E. For simulation needs, VTK offers tools for 3D visualization, although it is not specifically a CAD modeler. Overall, the discussion highlights the challenges of finding robust open source CAD solutions that can compete with established commercial software.