For a first iteration of the vest (or now belt) we found some nice encapsulated vibration motors - but they are no longer available. Pancake motors, which we wanted to use first, where not that reliable on the long run, and hard to solder. Our vibration motor of choise is now a standard, as small as possible vibration motor with external excenter (because they are easy to get :). To prevent the excenter to stuck in the pla of the housing, we make our own small encapsulation with a piece drinking straw (the excenter should be therefore have a smaller diameter as the motor housing, which should be a little bit smaller than the (5mm) straw diameter). The second importand choise are the electrical connectors of the motor: Wires are annoying, because they have to insulated. We chose instead motors with a spring connector at the end, which allows reliable soldering (with just small pads on the motor it might be prone to breaking) and will be encapsulated within the housing, preventing the need of additional isolation.