Hi Ralf,

re:
> Do you think its possible to make a automatic selection of these? Perhaps with the help of these new crv functions?

Some strategic use of selection and joining could help. For example with a cube+hole like this:



Go to the Top view and make a left-to-right window selection like this:



You'll get a selection like this:



Isolate these objects by right-clicking on Edit > Hide so they are the only visible objects:



Use Edit > Join and then select naked edges (http://moi3d.com/forum/index.php?webtag=MOI&msg=6051.2):




It really is a shame to work with data like that though - an STL file like would likely be coming from a CAD program and it's so much better to load in the original CAD data using STEP format for example.

- Michael