I've just made some prototype ribbons of irrational numbers accurate to 1m; significant figures vary according to model!
Unfortunately, I only realised after finishing the aptly yellow golden ratio that perhaps cherry pi, the square root of blue, and naturally green might have been a better use of colours... Next time, Gadget! I also need to figure out a better decimal point for the picot design on the e ribbon.
Photo below shows about the first 20cm of four ribbons.