GGtag is a reusable, reprogrammable ePaper-based badge with RFID.

Side note: It would be cool to allow exchange of payment information (such as lightning invoice) through sound rather than NFC.

https://www.hackster.io/news/ggtag-is-a-reusable-reprogrammable-epaper-based-badge-with-rfid-c9aed6b7ddd0