Put your Arduino in an Altoids case. This has blocks that hold the PCB and can be "melted" with a soldering iron or similar to keep the PCB in place. Also, there are 2mm holes that can be drilled out to your preference to use screws to hold the Arduino in place. There is 3 mm of space under the PCB, ample room for wires and leads underneath.
Access for USB programming, power, or other connections will necessitate holes through the Altoids tin, but I leave that as an exercise for you, gentle maker.
arduino_altoids_insert.stl | 85.8KB |