FreeCAD

FreeCAD is a general purpose platform for CAD development. It can be extended to use different workbenches to solve different problems. Targeted squarely at the engineering community, FreeCAD is an open source design application built to be extended. Python, the powerful scripting language, is woven deeply into FreeCAD's DNA and gives users unprecedented power to automate and invent.
"FreeCAD [How-to]" is a lean, fast tour of FreeCAD's major workbenches and design philosophy. The reader will get a hands-on introduction to several modeling techniques and learn how Python makes macro automation and design possible.
FreeCAD allows users to design in a variety of ways; from drawing 2D designs as lines and circles to combining primitive solids into complex 3D shapes. Objects can even be created or modified by code you write in Python. FreeCAD even allows power users to extend the application itself with new dialogs, panels, and scripts. This book will not only show you how to get started using FreeCAD in a traditional GUI mode, but will teach you how to harness its powerful scripting language for more power.