Rafter, framing & T-bevel are useful types of this "geometric" tool
[DOC] [TLE] A Geometric Study in Quartersawn | THISisCarpentry [PAR] Apr 8, 2016 ... Sketchup is a really useful tool for these types of large-scale layout ... a fairly 
reliable method using a torpedo level and a piece of scrap ripped on a bevel.