So many free viewers. We used to use Solidworks eDrawings, which was great, but they don't currently support the lastest Autodesk Inventor file formats. So now we use Autodesk Inventor View. However, this software is a bit too limited for many of our users. We're trying to do away with printed drawings on the factory floor, but this means the factor floor workers need to be able to do some basic manipulation on the model in order to get a view of what they need. Inventor View is more of a simple printing tool.

Hopefully, Adobe might come to the rescue.