I'm in the process of converting my office wall from HSW to Multiboard. As such, I'm looking for Multiboard alternatives to my old HSW things, especially for cases where the HSW-based thing uses the large connector. I really liked MG Print's holder but wasn't jazzed about the 2-part assembly thing. I found Patryk's remix, which was a single piece, but the ring was just too big to securely hold the hygrometer. Fortunately, MG published a STEP file, so mimicking his ring was simple. Meanwhile, I went with Patryk's idea of a single body, despite needing a tiny support and here we are!

I use these hygrometers from Amazon if it matters. Pretty much all of the round ones seem to be the same thing.