How work with CAD 'stl' imported object files I imported a CAD drawing of an airplane in 'stl' format into Blender.  I left the windows out, because I want to make them clear glass.  When I import the window separately, in 'stl' format, I am unable to make them glass &amp; transparent.
WFR
I just tried it with an STL file, and it works fine for me.  Steps I used:
1. File:Import:STL
2. Select file and import
3. Select the newly imported object (right click)
4. In the materials panel, add a new material
5. Check the transparency panel
6. Change alpha slider to desired transparency