So you have got a NFC phone? You can unlock it with a smart ring. We have already covered rings that can unlock your phone using NFC. But you could also make your own NFC ring or put a NFC tag in your nail polish. The good folks at Adafruit have put together a guide that shows you how to make your NFC ring, mod your Android phone to read tags from the lockscreen, and unlock your phone by unlocking tags. A pretty fun DIY project.