This guide first appeared on multimeterapp.com . Multimeter is a Mac menu bar app that turns any number into a live meter.

In about fifteen minutes you’ll make a face that shows a colored dot and the value, turns yellow and red at your alert levels, and works with every source from the battery to a number you send. If you know a little HTML, CSS and JavaScript, you have everything you need.

1. Create the face

In Multimeter’s Settings, click Create Face… (Option-Command-N) and name it Dot . Multimeter makes a folder of starter files and shows it in Finder. Open the folder in your editor. To see a change, pick the face in Add Meter… or Customize This Meter….

Want a head start? The source of all 35 built-in faces, plus two example faces, is on GitHub at multimeterapp/multimeter-faces (MIT license). Copy any of them into your face folder and change what you like.

2.…