I am working on a "semi-automatic pond refiller" project, and this model is part of the water level sensor component. This is a "capsule" for a Sharp GP2Y0A21 Infrared Sensor I already have lying around the house from a previous robotics project. I added a cylindrical shell on the outer rim so I can heatshrink the sensor wires and make it (hopefully) water resistant. The sensor itself is mounted on a PCB, with a plastic lens formed into the outer casing, so I am not worried about water getting in through the rectangular slot at the top. The screw holes are pretty arbitrary; I was hoping to dig through a box of random screws and find one to fit, rather than tailor the holes the screw. The two holes to mount the sensor (little "ear" cutouts) should be 3.36mm, if that helps. Edit: I ended up using some 4mm diameter by 25mm length screws, and adjusted the threads accordingly. I removed the outer cable support, since it seemed unnecessary and didn't print well without additional supports. The fitted cylinder "guides" were also removed when I added the three screw holes.