Technical drawings
Osifont is provided under GPL by hikikomori82@gmail.com.
My sty files are licensed under GPL as well. Feel free to use them.
Dimline
The din-dimline package is adapted from tikz-dimline, provided under WTFPL by Sébastien Gross.
din-dimline is explicitely not compatible with pgfplots.
Screws
Button head screw
Due to technical limitations, this is still drawn according to DIN 7045: In DIN 7045, it was always rf = 2*dk, so the angle of the button was always 60°.
With the new norm however, rf is a bit smaller, so the angle has to be calculated for every screw. For now, I can't find a way to do this with tikz.