Thanks, managed to finish this. I like moi3d more and more.

Result, very simple thing: http://www.thingiverse.com/thing:867528 (blue models there).

Another "basics" question. Could "save" be modified (script?) to prevent user from loosing data by also always saving in 3dm file?

Scenario:
- do some model
- save as 3dm
- do more work, click save button
- save as stl for test print or preview in 3d slicer for example
- do more work, click save
- close program... whoops I just lost part of work since it got saved as stl only.

I like different approach where save always saves in native program format (3dm in this case) and "export" exports to foreign file formats (possibly formats that loose information like stl). That way by clicking "save" work is never lost (since best format is used for saving) regardless if export/saving in other file formats was done in mean time.

My current workaround is to save file twice everytime I want to save - which means ton of clicking, confirming overwriting and that every time I'm saving progress (which is often). Pain.

How others are dealing with this?