One of my secret tools I use to make really fast mock ups to test folds is block of 1mm grid paper. Most of you might know about 1cm grid paper, but 1mm is way better especially you wont have allot of occasions that you have to measure something smaller than 1mm. No need for a ruler just count the stick lines for 1cm and the thinner ones for 1mm, put down some dots and play connect the lines.
Also its really fast and mostly its an eco friendly way to design cause you dont need to use energy for a computer and printer. Plus you don't have wait for startup and then also starting up the software, also cost time to make it and than also printing it. While in most of the time just fast drawing it on paper would have spent less time. However you might say if you did it on the computer you are sure to have the template ready if its correct. Yes if it is correct that is, but have to say experimental design, templates or folds its just to test it and rarely have to be accurate size. I rather make several fast mock ups to understand the design and them build the template in the software and after it just have to do minor changes.