Mobile phones with NFC are getting more popular every day. Samsung and Sony are selling (Smart) Tags and NFC stickers. The tags are quite a lot more expensive than the stickers. You can print this NFC keyfob and put the sticker inside. This video gives some background into NFC and NFC smart tags: http://www.youtube.com/watch?v=yLojs9PJi4I I am using these stickers (10 for 19.90E): http://www.verkkokauppa.com/fi/product/3750/dkcrt/MyFoneKit-NFC-tags-tarrat-10-kpl-valkoinen Samsung sells the square stickers, twice as expensive (5 for 19.90E): http://www.verkkokauppa.com/fi/product/13035/djtfq/Samsung-TecTile-NFC-tarra-5kplUsing the customizer you can create the 2 pieces making up the keyfob: a case and lid. Depending on the precision of your printer, the lid can just be pressed into the case, or you can add a bit of glue. You can specify the size of the sticker, you choose a round or a square shape and you define the size of the connection ring. The tolerance parameter is is the amount of clearance in mm between the case and the lid.