This is a relatively "eye-pleasing" box for the Anavi Thermometer:
https://www.crowdsupply.com/anavi-technology/anavi-thermometer. I have heavily borrowed from a variety of sources here to get a vented box that fits with the house. ... This is part of an openHAB project to control Sonoff enabled motors, driving zoning in a ducted A/C application.
While this is still a work in progress, I recommend looking at the original designs (see remix panel) that I borrowed from - the circlips are genuinely "unobtainium" and the louvres a neat print that I had to print to believe.
There are two sizes of pushfit "circlips" ... print without raft and invert for max holding. They fit snuggly - secure with soldering iron