I'm sure many of you on this website will understand the plight of not being able to get to a small tape measure or ruler fast enough to make a simple physical or mental measurement, whether it's as a reference for purchasing intangible items online, estimating materials for a project, or whatever everyday use you might need one for. Myself, I can either go for my leatherman on my belt or the mini tape measure in my bag if I'm out and about, but if I'm just sitting at my desk, often the absolute most convenient place to get a rough measurement is on the edge of my laptop. Mine has a 13-inch screen so I can easily fit a full foot ruler on the bottom edge. You might be worried about messing up your precious laptop a little bit, but (depending on the material yours is made of) they're almost invisible when I'm not looking for them, and in a way, kind of a personalized detail and give a bit of a workman-like aesthetic to my machine. And hey, it's always nice to have tools on you!
I suppose you can do this on other devices and objects as well. Personally, I never seem to have a ruler close enough to me, so figure out which object you are most likely to have with or near you, and apply this instructable to it! I reckon things like phone and tablet cases will be similarly improved by this technique.
Step 1: Secure Ruler for Marking Reference
I used a ruler taped onto my laptop as the reference for my marks. Make sure it's parallel to the edge or surface you are marking and not tilted off-axis, or it will result in inaccurate marks! Carefully seal as much of the tape's surface area to the surface of your laptop as possible by pressing in by the edges of the ruler, until it can't fidget easily.
It's not important that it be centered on whatever place you mark, but I made it roughly in the middle as my laptop doesn't have square edges so it's not much use for it to start on the corner.
You can mark whatever location you wish, but I found the very front of my laptop to be the best place for me, especially as it is the easiest place to put larger objects up against to measure them. I suppose this way I can also use it without opening the screen if I have to.
Step 2: Make Your Marks
I used the plain edge knife on my Leatherman Wave not only because it has the proper edge to make a clean mark, but also because the blade geometry is symmetrical so I can easily center it adjacent to the mark on the ruler I am copying. When you get down to this small a scale, that makes a difference. I originally tried using the serrated blade, but the asymmetrical grind and blunt sheepsfoot point make it hard to tell exactly where the edge and point are sitting on the material you are cutting.
I recommend marking the measurements furthest from themselves first and moving inward, as this will help you keep the ruler oriented, especially in case the tape comes loose or the ruler fidgets.
Very carefully align your blade adjacent to the line mark on the ruler, making sure the absolute edge is aligned with the line mark, as well as flat on the material, so as to cut all at once, and press just enough to cut into the material of your laptop. If your marks are not visible or long enough, carefully seat the edge into the rut made by the first mark, and do it again. I made marks for both inches and centimeters, making the inch marks slightly longer so as to differentiate them, as on a ruler.
I made the mistake of orienting the ruler wrong by not flipping it when I switched to centimeters, so instead of my centimeter and inch markings begin at the left as usual, they start in the right. It's not a big deal, but I'll just have to remember to measure centimeters from the right when I want to compare them to inches.
This isn't a super fancy or accurate way of measuring things, but I know I'm going to get a lot of use out it, especially since it's a whole foot and is always immediately in front of me if I'm already using my laptop.