When I want a specific 'ruler' cut, I make a paper template and take it with me to make sure the finished cut is right. First time the True-Value hardware guy did not compare the template with his finished cut--he was off on one side by 1/2". It was re-cut at no charge.
I draw lines on the top of the new 'ruler' then score with a utility knife, I then fill in the scratch with a fine point permanent marker. Lines are visible and work for me. That is how I made all my Twister rulers and also made a 10" ruler for layer cake cuts. Put cabinet door cushions on them so they do not slide around and you are in business.
Jan