I am thinking masonry/fireplace door installation. Each fireplace needs measured accurately before one can order a Fireplace door. Often times, customers opt to measure themselves. In a previous life, the company I worked for ran into so many issues and so many "rejected" doors that were used for floor/clearance models. Even if the customer did not do the measurement, installers would get it wrong. The measurements necessary for a Fireplace door include up to 12+ distinct measurement. The type of door (zero clearance, etc..) as well as door accessories are heavily dependent on the measurements. Imagine placing an order, waiting 4-8 weeks for it to be built and all to discover that it doesn't fit. Anyone interested in tackling this problem, get a hold of me.