This is the device I used to construct the ice spheres shown in Encodings in Space and Time. A water-filled container sits inside the roto mold shown below, which spins in a freezer as the water inside the container turns to ice. By modulating the rate at which the sphere spins, as well as the temperature in the freezer, I was able to vary the bubble structure frozen into the spheres, as well as the opacity of the ice.
For construction details, and some physics calculations, continue reading here.
The ice mold is 3D printed, and the two-axis rotational mold is CNC routed. The gears and metal bits were purchased or scavenged.
If you're a cocktail enthusiast, naturally you're thinking how this project might assist your next soiree. To step things up another notch, check out The Standard Model of Cocktail Physics, by my good friend David Harris.