Before we actually start putting pencil to paper (or rather mouse to CAD, in this case), we need to outline some basic needs and layout of the duck. Let's start with the problems and solutions analysis that we did on the design.
The following table lists the problems and solutions we worked up; although the original table was handwritten, this one is far more legible:
Problems we'll encounter
Water leaking into seams of the model
CA glue seams, and fill with silicone sealant.
Water leaking into the location where the propeller shaft meets up with the body
Stationary sleeve for shaft filled with grease and sealed (on the outside) with silicone.
Water leak on access lid
Silicone sealant o-ring.
In event of water leak, waterproofing Pixhawk
Silicone moulded Pixhawk case? (No).
Pixhawk heat from silicone moulded case?
Can't seal it. Must make body as water-tight as possible. Test water-tightness in every stage leading up to Pixhawk integration.