LibreCAD - An open source 2D CAD application for Windows, Apple and Linux.
Blender - Blender is the open source, cross platform suite of tools for 3D creation.
Autodesk AutoCAD - Autodesk AutoCAD is a commercial computer-aided design (CAD) and drafting software application.
Onshape - Onshape is the first full-cloud 3D CAD system. It runs in a web browser and on any mobile device.
FreeCAD - An open-source parametric 3D modeler
MatterControl - MatterControl is a free, open source app that lets you organize and manage your 3D prints.