I liked the original design very much, but it did not work as expected. had some problems with the clip mechanism. So I changed the file and printed and changed and printed.....
Finally I got a design which works great for me.
The real credits for the original design go to Andreas Kahler (http://www.thingiverse.com/drayde/designs). Thanx for the cool design.

The thin walls are 1,4mm.
I use Kisslicer to slice my parts and need 0,1mm Surface insets so I choosed a extrudion wide of 0,6mm --> (0,6+0,1)*2=1,4mm
Layer heights from 0,15 to 0,3mm worked all pretty fine for me.
I printed the part in PLA and ABS. Both work good.