This is a case for the HC-SR04 ultrasonic sensor. I made it especially for outdoor use because I need a sensor for measuring the water level of water tanks.
The sensor cable can be fixed with a cable gland (M12).
If you fill the case with epoxide resin after installing and wiring the sensor the case will be waterproof. Keep in mind that the sensor "eyes" are not waterproof.
There are several types of HC-SR04 with different dimensions available. I made this design for a sensor 45.5mm x 20.5mm and a distance of 27mm between the two "eyes".
Use support for the cover (snap-in noses) and the case (snap-in and hole for the cable gland).
The pics are showing a printout with Extrudr NX2 Yellow filament. I strongly recommend Extrudr Greentec or Greentec Pro for outdoor use .