Measurement Tools for Laying Out Circuit Boards and Enclosures

When laying out panels or circuit boards, accurate measurements are a must.  A few inexpensive tools can make excellent results much easier to achieve. 

I think we've all used rulers to try and measure parts.  For the fuse holder shown, it can be held against the ruler, the width estimated and the marks correctly interpreted to get a decent result.  The ruler shown is a high-quality metal ruler and it has metric units on the back.  I use a combination of inch and metric units depending on what size something is designed for - for example, in laying out PCB dimensions, I'll use whatever units the enclosure was designed in.  Usually, one system will provide nice numbers.