Reuse: Ultrasonic Jewelry Cleaner. I Made It at TechShop.

Goal:
      To reuse discarded electronic toothbrush.

Design Requirement:
      * Do not create the cup.  Use existing cup.
      * The cup need to be light so it would not take a lot of force to vibrate the water in it.
      * There connection of the gadget to the cup need to be strong.  This way, the vibration transfer would be most efficient.

Procedure:
      * I would use Autodesk Inventor or Fusion 360 to design the gadget.  
      * I would create .stl file to do 3D Printing.
      * Alternatively, we could perhaps spray a few layers of lacquer paint to make it impermeable.  Spray each layer and let is dry before putting on the next layer.

Update:
      Like the ultrasonic funnel, I will post video of this gadget.