When you hear the term Tricorder, you might think of Star Trek but I assure you, this is no toy prop. Keeping with the same concept of the Tricorder used on the TV show the Tricorder is about reading data, _lots_ of data. And that is what the Tricorder project aims to do, develop handheld devices that are fitted with lots of diverse sensors in order to observe them.
So far the project has produced a few different versions. The Mark 1, the Mark 2, etc. They are currently working on the Mark 5. Each version is pretty different from the other, and they all contain a wide variety of sensors such as atmospheric temperature, humidity, pressure and electromagnetic field, color, infra-red. And the obvious like GPS. They’re even working on developing their own sensors like this 3d printable mini spectrometer.
The project is open, and there are tons of pictures, and schematics on the tricorderproject’s web site.