Donphan consists of a single 8-inch diameter acrylic tube, which houses all electrical components; two machined aluminum side plates, for mounting the majority of external components; an additional base plate for mounting the downward facing camera and other equipment; two side mounts for the vertical thrusters; and a rear mount for the back-facing thrusters.
The objectives of this design include modularity and reduction of drag in the water. To ensure easy access to all of the sub’s internals, six nuts on the half-inch diameter threaded rods can be removed to quickly access all of the internal electrical components. The screws at the bottom have their threads filed off at the end so that they can slot into the base plate as pegs, while still being easily replaceable. In addition, the surface area perpendicular to forward motion was minimized to achieve minimal drag.
During the prototyping phase, several of Donphan's mechanical components were 3D printed at a smaller scale and test fitted to ensure that the manufactured version would be modular as intended.