Modelio - Modelio is an open source modeling tool supporting natively UML, BPMN and model exchange with XMI.
Blender - Blender is the open source, cross platform suite of tools for 3D creation.
Diagramo - Diagramo is an online flowchart software - diagrams (create, edit and share)
FreeCAD - An open-source parametric 3D modeler
ARIS Express - ARIS Express is based on the proven ARIS methodology and industry standards.
MATLAB - A high-level language and interactive environment for numerical computation, visualization, and programming