I met the founder of Grabcad when he made a trip to Shenzhen China around 2012. I took away that he was trying to build the "github for CAD". We tried the Grabcad system out in our office for a while and it was useful but didn't really meet that vision. I haven't tried it since the company was acquired by Stratasys in like 2014 but a quick login looks like it hasn't changed much.