= Engineering effort applied to freely publish useful engineering data and designs such that others may freely reuse the information.
Examples: A wood stove design others can build, modify and deploy as they please.
- CisLunarFreighter/Open source tools 
- NASA Will Tinker With Open-Source Rocket for Return to Moon 
- algOS - Oil from Algae Open Source 
Tools which may be useful to participants in engineering studies, research and development.
Looks extensive, useful and increasingly so. Not terribly easy to install and maintain for a computer neophyte.
Finite element analysis package. Freeware with C source code downloadable. Program documentation available in English, German and Greek.
List of links to open source or free engineering assets.
List of Free Math tools maintained by the Wikiversity School of Mathematics
GUI based geometry editor. Includes some analytical functions, geometric shapes, conic sections and exports to several formats including SVG. Good for sketching and diagrams.
Math analysis and plotting tool for Linux/KDE desktop environment. Superimposes functions on precise plots and allows export to bmp, png, and svg.
3D CAD tool
Computer-aided engineering platform (CAD, kinematics, analysis)
- Electric Editor VLSI CAD system. Available under the GNU Public License.
Latest version at ftp://ftp.gnu.org/pub/gnu/electric .
- Alliance CAD tools available under the GNU Public License.