The waterproof case consists of two parts (top and bottom), is sealed by a silicone seal and held in place by a rubber band. Feel free to print one yourself or have a look at Shapeways if you do not have access to a 3D printer.
Some very decent print result was achieved with the following setup
- Prusa i3 MK2
- 0.4mm extruder nozzle
- Infill 20%
- High quality PLA, preferable white color to better see the charging LED
- Support structure for top of the case with some additional support blockers
- Print time for top and bottom about 4 hours
The main silicone seal is borrowed from AMP Superseal connector with 6 positions (Digikey Partnumber A106530-ND). Any rubber band with decent tension is good enough to hold to top and bottom of the case in place.