This is a necklace or collar with a vibration function. The vibration will be turned on when you move and gets more intense when you shake our head eg. while dancing. Or the vibration function will be turned on remotely by your friend.

The collar can be secured by a solid clip closure at the back of the neck. At this place the vibration motor is positioned which gives an intense vibration especially at the back of the neck but also at the whole neck. In the front there is a solid but easy to close hook closure.

For the vibration you need the body interaction vibrator development board. It is inserted into the collar and controls the vibration motor. The more you move the more it vibrates. There is also place for the battery. Wires and boards can be hidden. Unhidden it has a scifi look alike.

Edit with Tinkercad https://tinkercad.com/things/8stCwczMAkp
More information at http://bodyinteraction.com/2016/02/18/vibrating-3d-printed-necklace/
http://www.bodyinteraction.com/product