To reuse discarded electronic toothbrush.
* 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.
* 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.
Like the ultrasonic funnel, I will post video of this gadget.