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Hi,
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Do you absolutely sure, that you are using AutoCAD 2011?
What OS do you have on your Mac? A'm asking about this because AC 2011 is compatible only with 10.5.8, 10.6.X and 10.7.X
Plus with STLOUT you can export only solids and watertight meshes ("closed" meshes) from the drawing, all other objects will be ignored.
Maxim
I don't have AC 2011, but in AC 2014 I was able to export your DWG to STL file. See attached ZIP archive
Maxim
Here is the attachment from my side:
I did it as usual, from menu File -> Export -> select STL file type from the list of file types, than give the name to the file, pick OK, select objects you want to export, hit Return.
Maxim