a key holder with a pocket for those keychain tags that have an RFID chip.
RC522, https://de.aliexpress.com/wholesale?catId=0&initiative_id=SB_20191111162102&origin=y&SearchText=RFID+Kit+RC522 has a number of those.
The use case is like those key holders you find in hotel rooms: you put the tag (attached to the keys) in the pocket and the RFID reader inside detects which tag it is and when it recognizes the tag, it will power up the lights and flag my presence in the smarthome control system as TRUE.
Both the pocket and the top need a 180° rotation when printing.
In so far it is the same as with it's prior version https://www.thingiverse.com/thing:3242266 (which has a more detailled description)
What has changed? - redesign in Freecad, sources included - window for a .91" OLED display - mounting points to fix an ESP8266 nodemcu v2 (amica) with m2 screws - the pocket is a separate object now that is attached to the top by 3 small pins - so no more need to print with support The top has been designed in a way to allow the rfid reader be as close as possible to the surface. Too much distance here had been a problem in the prior version as it caused unreliable recognition of inserted tags.
There has been an update already, I added an additional screw hole at to top of the top shell to allow to have a little clip that helps keep the display in place (use something from a misprint with a 1mm hole for the screw)
Things to care for: The srew holes are a problem, you will have to prime them with a manual drill to make the m2 screws go in. M2x20 at the 4 corners, m2x4 to fix the mcu and the clip. The rfid reader and the display need some glue to fix them, I use UHU patafix for that. (recommended)