Turn any surface/wall/table etc into a speaker with a surface transducer. This type of speaker does not have a moving cone like most speakers you've seen. Instead, a small metal rod is wrapped with the voice coil. When current is pulsed through the coil, the magnetic field causes a piece of metal to expand and contract - and if it's pressed against a surface it turns the transducer into a speaker!
Often these size transducers are pressed up against a flat surface to turn it into a sounding board. The effect is a surprisingly clear sound that comes from the surface itself. The body of the transducer is heavy so that it can be placed with the rubber top down on a table. And for another fun trick, put the transducer at the end of a large plastic cup to point sound in a particular direction.
This transducer is about 28mm in diameter and has 4Ω impedence and should be run at about 3W. It pairs great with any of our audio amps such as the TS2012 breakout or MAX98306. Just connect it as you would any other speaker, we even have some wires pre-soldered on.