Today’s lesson for startup founders: Building software for overlooked industries can have big rewards. PlanGrid, which builds software tools for paper-dependent construction workers, agreed to sell to design-and-construction software provider Autodesk for $875 million, the companies announced Tuesday. It appears to have been a lucrative sale for PlanGrid and its investors, which include Sequoia Capital, Y Combinator Founders Fund. The Information reported last year the startup’s valuation was about $400 million. Autodesk, which already sells software to large construction companies, says it expects PlanGrid to contribute $100 million in annual recurring revenue by 2020.