Arvind Singh (forum user vindar) made an amazing acoustic levitator.

An acoustic levitator uses sound waves to levitate small objects, and until a few years ago were expensive to construct using Langevin horns that required tight tolerances and operate at high voltages.  Asier Marzo from Bristol University published a paper demonstrating how an acoustic levitator can be constructed from off the shelf parts and run on low-voltage.

Arvind built a levitator from an Instructible project based on an Arduino Nano, then decided to improve upon it by building one with a Teensy 3.2.  The processing power and memort of the Teensy 3.2 allowed for additional options to be added such as a TFT display and a joystick.

The casing was 3D printed using wood PLA then stained and varnished making for a beautiful device.

Code, schematics, and STL files are available on Git Hub.