I’m doing quite a bit of travelling at the moment, and the megameter is the kind of project I can stuff in my rucksack and take with me.
It would be nice to have some sort of case to keep all those vulnerable electronic doodads covered up; as luck would have it, the case for an old pack of Beano playing cards is the exact same size as the PCB.
I used a spare soldering iron tip to make a hole and slot for the LED and logic header, and then rolled a very thin blu-tac sausage to stick the edge of the case to the PCB. Surprisingly, it’s rock-solid; blu-tac sticks very well to solder mask, and the case is near-impossible to prise off.
That should keep things safe for now!