The traditional Arduino board design, as found on the Uno and variants, lends itself well to experimentation - especially when coupled with our Arduino Prototyping Bundle (ARDP), which combines an adhesive solderless breadboard with a custom-cut acrylic backing plate to keep everything neat and tidy - but it can sometimes be awkward to mount in a finished device. Thanks to Thingiverse user stkoenig, things are now easier for those building certain classes of devices via a clever V-Slot mount adapter.
OpenBuilds' V-Slot is a clever modular aluminium rail system which is commonly used when building devices with moving parts such as laser cutters, 3D printers, and CNC mills. Using stkoenig's 3D-printed adapter plate, it's possible to mount an Arduino Uno - or any compatible board which follows the same design, such as the older Duemilanove - directly to the rails of a V-Slot system. With Arduinos proving extremely popular for providing the driving logic in such a system, that's a great feature - and one freely available, thanks to the release of the files under a permissive Creative Commons licence.
The files for the mount can be downloaded freely from Thingiverse, while more information on V-Slot is available on the OpenBuilds Part Store. Remember, too, that you don't need to own a 3D printer to make use of stkoenig's design: your local hackspace will almost certainly have a 3D printer you can use, or there are web-based services which will print any quantity you desire and send it to you ready-to-use.
UNO mount V-Slot 20x20 Nut 6 by stkoenig is licensed under the Creative Commons - Attribution - Share Alike license.