Hello Ben,
According to statistics, approximately 225 mobile phones are stolen every hour in Argentina. A well-known theft method is pulling it while the owner is holding it in the hand, either while reading or talking with it, then run away with it. Sometimes they pull it while getting off the bus, using the momentum, and sometimes from behind using a bicycle or motorbike. It would be nice being able to create a mechanism to prevent the phone from being stolen under those situations. I've seen some people using straps around the wrist, some using a sort of chain to the waist, but most phones no longer come with holes for straps. We use different relatively large phones (Samsung S6, LG G4, Samsung Note 4, etc), but if it could also work for smaller ones it would be nice.
Regards,
Roberto