Getting a perfect measurement is rule number one when you're making pretty much anything, but it's easy to get lazy about it and just quickly draw out a line without thinking too much. Over on Instructables, Popular Mechanics reminds us that if you really want a good measurement, you need to hold that pencil at an angle.
If you hold your pencil straight, you'll get an inaccurate measurement. Sure, it's just a millimetre or two, but that can make all the difference:
When marking a line with a ruler, be sure to hold the pencil at an angle so that its point meets the workpiece at the same place the ruler does. Holding the pencil perpendicular to the work surface results in the center of the pencil point being inaccurately positioned.
Any woodworker or builder should already know this, but it's still a nice reminder. Head over to Instructables for a bunch of tips on getting those measurements perfect.
How to Measure and Mark with Precision [Instructables]