Why not handle data via a 3D-PDF file?
It is possilbe to use a 3D-PDF file as a CAD-viewer and as a data-container incl. 3D-CAD files, manuals, drawings etc. etc.
Look at our examples:
http://www.archnav.de/archnav_Crane+Fast_Rescueboat_rev1__.pdf
http://www.archnav.de/MAN_Diesel_Engine_MAN_6S42MC_rev2__.pdf
It will be great if grabcad is following the same approch.
Cheers
Bernd