C-mount extender

C-mount extension tubes of different lengths.

Update 08/2018
* Fixed thread pitch of the outer thread (was 0.75mm, corrected to 0.794mm=1/32").
* Added more tolerance (0.2mm on the thread diameter instead of 0.1mm, for each of the threads).
* Reduced model resolution in order to bring down the file size.

Printing
Because of the relatively fine threads, a layer height of 0.15mm or smaller is recommended. Obviously, for the thread to work smoothly, the dimensional accuracy has to be quit