The Mug+ is a clever device that formalizes a trick many thrifty hosts are probably already familiar with. Anyone who's hosted a small gathering of friends but been short a set of speakers knows that placing a smartphone in a cup, glass, or mug and playing the music aloud amplifies it. The Mug+ is a Bluetooth speaker that uses that very same concept, turning any concavity into a working speaker cabinet.
Essentially, the Mug+ is a Bluetooth speaker that abandons its housing. Suitable for openings between six and ten centimeters wide, it can be placed on the mouth of deep objects, turning those objects themselves into the speaker's echo chamber.
The developers of the Mug+ note that different materials emit different sounds. For instance, ceramic mugs tend to be dynamic in the upper register, while paper cups have a resonant mid register and metal containers are relatively even across all frequencies.