ShareX - ShareX is a free and open source program that lets you capture or record any area of your screen...
OpenSCAD - OpenSCAD is a software for creating solid 3D CAD objects.
Greenshot - Greenshot is a free and open source screenshot tool that allows annotation and highlighting using the built-in image editor.
FreeCAD - An open-source parametric 3D modeler
LightShot - The fastest way to take a customizable screenshot.
ImplicitCAD - ImplicitCAD is a programmatic CAD program, implemented in Haskell.