Hand span 1 point perspective tool.

The problem I was trying to solve is how to setup the proportion my drawings on my paper & vanishing points, while locating the drawing in the real world with vanishing points. I don't think this is a complete solution, but its a start.

This lets me start a picture on a square grid (1/3, 1/3, 1/3 horizontally and vertically, with the main bulk of the drawing occurring in the centre square... or when I get better at imagining things and drawing converging lines, expanding the centre square to fill the page.)

My bio metrics are awesome! I don't know if these ratios will work out well for anyone else. I think they will be close though.

This is a 1 point perspective solution for the moment, but most of this applies well to 2 point and 3 point.