PlanGrid was a YC one that eventually got acquired by autodesk for $875m on $69m raised.
https://techcrunch.com/2018/11/20/autodesk-agrees-to-buy-pla...
First HN post: https://news.ycombinator.com/item?id=3659159
https://techcrunch.com/2018/11/20/autodesk-agrees-to-buy-pla...
First HN post: https://news.ycombinator.com/item?id=3659159
Only difference is we deal in 3D rather than pdfs, and we're open source for too many reasons to type on a mobile phone, but happy to elaborate if needed.
I think what is fascinating about this space is that the tech is there for full 3d models, machine control, and BIM smart design.
It's all just so expensive, only the huge companies get deep into all of it. As a PLS, we've been delivering site topos for decades with full 3d surfaces, only to deliver those to the engineers and after design they print out a plan set.