Blender Guru - Awesome new feature! The "Ruler/Protractor" button. Allows you to click and drag anywhere to see the measurements :) Download the latest build to use it: http://builder.blender.org/download/ | Facebook
Latest features in Blender for CAD users | Rainnic in the Clouds
Blender 2.8 Viewport Ruler (For User Preferences) — Right-Click Select
Ruler and Protractor — Blender Manual
Blender 2.66 r55116 3D Ruler & Protractor Tutorial - YouTube
Systèmes de cotations dans Blender
167- Blender - Ruler Protractor - YouTube
customization - Ruler/Protractor tool - change text color - Blender Stack Exchange
Buy Huanyo Protractor Ruler 180 Degree For Math Geometry | eRomman