Thank you all for the comments!

If one day my boss/company don't like me anymore, may be I start then a serial production and sell such air screws. But this is so much effort, I have some doubt, that the work pays off.
One more question on soldering: is there any specific reason why copper tip is crucial?
There are some "life soldering tip", but copper has the best heat transport and there is a better connection between solder and tip. May be the other are working too, but I tried it and was not comfortable to a slightly different behavior. Hard to explain
Can't see the pics Frank 
Guy, they are stored at Google, but I noticed sometimes a delayed loading. If the pictures are not there or only partly, try a reload of the page with the browser. Should work!
Cheers,
Frank