While everyone in their right mind would love one of those fancy giant ice ball makers that go for $1300 and up, they're not the most practical solution for the home mixologist.
So I used my superbrain and did all sorts of math with equations and integrals and all, and came up with a way to make these at home:
(glasses by CB2, by the way)
To see my highly scientific secret method, continue reading after the jump...
I used water balloons ("water bombs" according the manufacturer) that cost five bucks for 400. Slightly cheaper than a fancy machine, and seriously, who doesn't like balloons?
Note: Ice balloons are for drink cooling and refreshment purposes only. Do not throw frozen water balloons. This may lead to serious injury.
An index of all of the ice experiments on Alcademics can be found here.