I needed a project case for my Raspberry Pi Zero W -based WiFi ultrasonic distance sensor.

This case had to house the Pi Zero, a battery pack, and the sensor itself. I also wanted it to be able to clip easily to my boat 1" handrails and decided to design one that would fit over like a saddle to keep the centre-of-gravity low.

Here is the design model:

The screw tabs on either side of the lower part are designed to hold spring clips as well as retention of the lid.

The original lid design had a flush-mounted sensor held in with hot-melt adhesive. 

Unfortunately this caused the readings to be intermittent or wildly out. I'm not sure whether the heat damaged the sensor or whether the overall arrangement was too rigid; causing the receiving part of the UT sensor to interact with the sender. However, I decided it was best to redesign this so that the sensor board was the only part in direct contact with the lid.

I also opened up the lid design to create more space and increased the size of the screw mounts.

Here is the completed unit with the sensor installed and all the main components:

If anyone wants to reproduce this, I have uploaded a zip file containing the two STL models.

Incidentally, the completed design is very buoyant - will float easily, even with batteries and everything installed. You wouldn't want any of the electronics to get wet, but at least it won't sink altogether!

20th October 2021