With a 100% infill and 2mm thick walls and using silicone aquarium tubing the design is sufficiently water resistant meaning it can be out in the weather, dropped in the water, and even fully submerged (for up to 10 minutes) without allowing any water inside.
However, the nature of 3D printing plastic means that there is always the chance that water can eventually make its way through the layers no mater what the infill percentage. We've submerged this design completely under water for 1 and 2 hour intervals at a time multiple times and find that a small amount of water eventually makes its way in.
Better sealing material and some sort of protective paint or epoxy on the outer surface could likely solve this problem.
This box is part of a larger greenhouse project that will require weatherproof enclosures and a growing environment that is highly controlled. Learning the limitations of 3D printing for extreme objectives like waterproofing will help inform the design process of future systems.
