It works flawlessly, even better than ice ball mold molds because those leave seams around the circumference. The ice balls that come out of this thing are seamless, perfect spheres as long as your ice block is big enough. As for how to source such ice, simply use an insulated 20oz tumbler, fill about 80% full, leave in your freezer with no lid for about 24-30 hours, let thaw long enough to release the ice from the interior cylinder walls (about 30-45 min); and voila, you have an ice cylinder ready to be pressed into a sphere. If you do it right -- that is, don't let the water in the tumblers freeze all the way to the bottom -- your cylinders will come out crystal-clear and yield crystal-clear spheres.
K. Kittinger 
