I got a simpe enclosure printed for the logger a while ago, thanks to the guys at Moon Wearables.
The battery is glued to the bottom half..
... while the top half has a hole for the push button and a little button that goes in it.
The button rests on the pushbutton on the PCB, and has edges that keeps it from falling out.
The PCB rests on ridges inside the bottom half and is glued in place. Ridges along the edge of the two halves and a bit of tape make sure that they lock in place. The HC06 bluetooth module is a bit awkwardly placed, I must admit that, but that means there will be room for improvement on the next revision, for example to let the module be soldered directly onto the PCB.