Hi Jukka-Pekka, thanks for posting the example file. Could you also post an example of the desired output? That would then help to clarify some additional things like if you're looking for a planar face as output or if you are looking for curves as the output.

Also when you say "goes onto the next" file, how would the script know what the next one is, is there a particular naming convention to them or do you mean pick it from a file dialog ?

Thanks, - Michael