Or just forget the watch and casing and build an add-on to the strap to hold the NFC chip. This should work with any watch strap that isn't metal. Similar pro

Or just forget the watch and casing and build an add-on to the strap to hold the NFC chip. This should work with any watch strap that isn't metal. Similar project I did to carry a microSD memory card. https://www.thingiverse.com/thing:6784665 https://www.thingiverse.com/thing:6784665