The Lumo Lift is a pretty neat posture and fitness tracker. I thought I'd open it up for the sake of design to find out what makes it tick.
The shiny metal thing in the middle covered with tape is the button mechanism. The cylinder on the underside is probably an eccentric rotating mass style vibration motor. The outer wall thickness of the unit is 0.7mm and that inner wall lip is 0.4mm (pretty thin! I actually damaged it opening it up). The inner lip's function is to mate the main casing to the lid, so the whole unit can be pressed like a button, which is pretty cool. The PCB is also surprisingly only 0.4mm thick - it actually flexes it's so thin.
I love how the magnet that mates the unit with the dock has to work through the PCB and battery to make contact, perhaps this is part of the reason why the PCB is so thin?
Overall the design is simple and elegant, but opening it shouldn't break it, so perhaps it's a little too delicate. Overall, it's a pretty cool design.