The voting should be between the participants themselves. Each of them should vote on a 1 to 10 scale to others who participated. Once everyone has voted, the one with the most votes wins.
That's actually not a bad idea. Eliminates sock accounts and vote padding. The only people who can vote are the creators themselves, they cannot for their own design and have to rank every other design submitted. Then, at the end, a winner will emerge chosen by the artists themselves.
Obviously I'm just an observer and have no stake in this whatsoever, but I think that could actually be a good solution.