I’ve used this one for the RAK Wireless boards:

https://www.printables.com/model/286657-rak19007rak5005-case-for-meshtastic

And this one for the Lilgo T-beam:

https://www.printables.com/model/127253-t-beam-v1x-case-for-meshtastic

There is a nice looking desktop style case for the Heltec devices here. I haven’t tried it myself yet and it’s not a free download, but I know one the guys in our local Meshtastic group here has used it and is happy with it.

https://www.zerofox3d.com/products/bender-heltec-v3-lora-meshtastic-battery-case-print-download