I find it's best to rapid prototype most physical designs and that is exactly my strategy with this project. I spent as little time as possible coming up with the design for this first casing, in the comfort that it was going to be fast and heavily modified with future revisions. Inspired by not very much at all I simple started hacking away! Sending what I dreamed up over to the 3D printer and hoping for the best.
(Drawn up in Fusion360 and very sloppily rendered in Blender)
Luckily, this strategy is already paying off as I immediately encountered some poor design choices that we're valuable lessons to learn now and not on version 50. Such lessons as 'make sure there's enough room to actually fit the part in' for example.
Also, as luck would have it, I've decided to add another small feature to the project which is a potentiometer that allows the user to select the range of the sonar/range finder before selecting the function you'd like to use. So the second version of the housing will have to already have to account for the extra hardware.
I'm very much enjoying this build! Having the first physical prototype in hand is such a wonderful feeling and I'm looking forward to the next round of revisions.