Round ice

 Novelty ice tray for golfers. 

They do go to extravagant lengths for round ice balls. Why? No edges to melt off quickly. Longer lasting. That is the theory. They make all kinds of specialty molds. Jumbo ice ball molds. Molds in the shape of 2-piece spheres. Some use a heavy weight to shape a cube.

One way to get clear ice is to use water that has been frozen. That whole bit about boiled water, twice boiled water, distilled water, filtered water and such is all nonsense. Another way is place an ice tray elevated in a small cooler surrounded with water or insulation so that the freeze tray becomes the center of a block, lid off, it must freeze from the top down. Then chip out the tray. Some methods control for time so that the process is stopped before completed so the bubbles that are pushed downward are stopped before the whole thing is wrecked by expansion.