The model is fully 3D printed (no extra parts required) and the lid and box should just snap together, although this took quite a bit of work from me and a little bit of lost material, but this ensured the hinge was as strong as possible. 

The bottom of the box has a sloped base and small holes to allow water to flow out, so for this I would recommend slicing with a variable layer height (gcode attached for MK4), and also keeping the box on a not-so-flat surface or a small cloth may help as the base is so flat it forms a seal with other flat surfaces - this may not be a problem with textured build plates. 

It also has a closing latch mechanism which has not given me any problems.