The Spherical 3D Printed Speaker
This speaker is not only 3D printed for under 100$ but it also projects close to perfectly spherical sound. In other words sound goes all directions.
At normal listening distances, an array of twelve speakers arranged on the faces of a dodecahedron is a very good approximation of a point sound source, and the sound waves it produces are very close to perfectly spherical. A dodecahedron speaker can be a useful tool in acoustics research, and is definitely a fun toy to pull out at parties. They are available commercially, but very expensive. Some people build their own, but the odd compound angles and the high degree of accuracy and precision required in the parts make for challenging work with manual tools. But it’s easy for a 3D printer.
There is even a tutorial on how to build your own (that is if you have access to a 3D printer), you don’t even have to do anything but press “print” because the 3D files necessary are available for download!