It's a snug fit, but not too snug. It can be printed with or without supports but the bridging will make the fit a little bit tighter. The cutout at the bottom is just to get a better grip, but you'll probably need to tap it a few times to help work it out of the channel, or put a ribbon behind the hygrometer before inserting it, to help pull it out when it's time to change the battery.
The author remixed this model.