Before I started studying computer science in university, I was working as a laboratory assistant in a paint coloring laboratory. One of my tasks was to do colorant characterizations to our custom-built (the company had one programmer) application so the software can approximate formulae for hardware stores.

This was really manual work. You needed to do different mixtures with the colorant and the paint to get an even spectrum of colors from light to dark. Everybody just started to do them randomly, calculating approximate mixtures, doing draw-downs, measuring and repeating until the result was good enough. I started playing around with excel macros and studied how Kubelka-Munk formulae worked. I even realized that there are lots of colorants using the same pigment, but with different strength.

When getting these numbers and some old measurements I built a big excel file with macros, where you just type the pigment data and it would print you instructions what to mix and how much. This saved several days in the process and finally they let me learn Delphi and convert the excel file into a real program.

I wouldn't want to read that code nowadays, but I think they're still using it in the laboratory.