Don’t Start Folding Yet! Let the Auxiliary Ruler Help You Mark the Perfect Fold Lines

We need the right tools to get things done fast, and the better tools the better productivity. As someone who designs paper art, tools are especially important to me when it’s time to assemble the final product. On a paper model, it means to cut out the parts from the expanded view, fold them according to the mountain and valley fold lines, and then glue them together with PVA.

There are several keys to a beautifully assembled paper model, for example moderate paper density, precise cutting, neat folding, the right amount of glue and keeping a clean appearance. This article focuses on the folding aspect of paper model making, which many paper enthusiasts or beginners often neglect. Before cutting a part you will have to mark its fold lines first, especially on papers with high density, so you can get clean flaps with no wrinkle. Generally, a scriber or a dry ballpoint pen, with the help of a ruler, are preferred for marking fold lines.





The fold lines of a paper model are scattered all over the paper, and unlike cut lines, they are usually circling around the edges of every part, and in different angles. This makes marking fold lines difficult, because you have to constantly move the hand that’s holding the ruler, and to top it all off, adjusting the ruler to align with the angles of the fold lines is a complete disaster. Your hand is always switching positions anywhere from 0 to 90 degrees repeatedly, which can be really exhausting. Luckily, out of laziness, I have come up with a ruler that’s designed specifically for marking fold lines, just to improve the experience on this task.

To start off, draw a sketch on a graphics editor, and try to get something that might work through brainstorming. The blue area is the auxiliary ruler for marking fold lines.


This design comes in the shape of two octagons on both the outer and inner edges, with the difference of 22.5 degrees. The idea is that this ruler is transparent, and has 16 straight sides and 8 angles. You use this transparent ruler by moving it to a fold line on the paper with your left hand, find the straight side that has the closest angle to the fold line, and mark the fold line with a scriber. This ruler helps you swiftly accomplish the marking process with the least movement possible.

Before start making anything, let’s do a little analysis of how much improvement on switching angles this ruler can help us achieve, with a spreadsheet:


When marking fold lines with a ruler, your left hand might rotate anywhere between 0 and 90 degrees. With this new octagonal ruler, the range decreased to 0 to 11 degrees, which means in actual practice, your left hand only needs to move ⅛ of the original range.

With this impressive analysis result, we can happily start using the auxiliary ruler. The ruler has to be transparent, so I used the lid of a powdered milk can. Not only is recycling environmentally friendly, the lid itself is also somewhat elastic, which means when marking lines on it, it won’t be too abrasive to the scriber like a metal ruler would, or if it’s a hard plastic ruler, the scriber might damage it instead. The materials and the finished product are shown below. They are easy to acquire and put together, and this is meant for all paper model enthusiasts, you should definitely give it a shot!




For more paper models and tutorials visit Fun Paper.



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