after many concertations, we want to make a prototype that we can put on the arm. But it can be put to another place. The magnet needs to move a lot and if we put it on the arm, it will move like we want when we’re walking (lot of people are moving every day, at least to go to the workplace) . If we’re walking 20 minutes at 5km/h , it’s more than 2000 movements for the magnet in the solenoid.