FreeCAD -

ThanCad is an n-dimensional cad, with raster inclusion capability and emphasis in engineering. It is being written in Python and since it uses the Tkinter library, it is platform independent! It is also easy to translate it to various languages

TigerCad is a lightweight and easy to use technical drawing utility. Ideal for garden design, mechanical engineering drawings, electrical / electronic, building and room plans and general diagramming. Output in PDF format for the web.Copy and paste graphics. Create standard symbols to re-use. Scale, mirror and rotate. Accurate scale drawing printing. Drafting tools to compare with pro packages. Unfortunatelly - not any import!

VectorEngineer Quick-Tools is a complete technical drawing and multi-purpose cad software system that offers all the features required to create accurate professional drawings, working drawings, designs, plans, layouts and diagrams in a quick and easy mouse driven windows environment.