CacheCAD

CacheCAD is a file management interface for Google Drive™ that allows selective syncing of files. This makes it ideal for managing engineering or CAD projects where multiple users need to edit files. CacheCAD is ideal for use cases where traditional feature rich PDM software is too cumbersome.

All user setup, permissions, and sharing settings are handled through the Google web interface. Which means you don't need to worry about CacheCAD having accessing to any of your data.