Another link to an interesting report about a project in which a RC522 RFID reader was installed as an input station in a LEGO housing, the whole thing then very thoughtfully implemented with a microcontroller on 8266 basis and RasPi and software-side with Homie MQTT and implemented in NodeRED. All very worthwhile approaches, imho definitely worth a deeper insight regarding the chosen application technologies. And since LEGO bricks can be produced quite well in 3D printers nowadays (there are enough templates on thingiverse.com), the case can also be built without having to raid the children’s LEGO box.

RFID Scanner – WeMos, RC522, Homie MQTT & Node-RED