"I see you have constructed a new lightsaber. Your skills are complete. Indeed, you are powerful, as the Emperor has foreseen." The lightsaber prop to own all lightsaber props, complete with crystal chamber and a blade bright enough to blind with the lights switched on. TL;DR? YouTube vids - with the blade attached; the crystal chamber. [via Geekdad, via Make]
RONJA is an optical networking device that can be built by nearly everyone, using readily available components and using only free software.
LED Throwies (QT) A simple combination of lithium battery, diffused LED, strong magnet and a little tape. Developed by the Graffiti Research Lab division of the Eyebeam R&D OpenLab, full instructions are posted and take only a few minutes to follow.