A young lady from Long Island has recreated Elsa's gown, and it's just ... insane. According to her tumblr, she spent about 200 hours working on it, and the dress is embellished with 100,000+ rhinestones. You can read about her process more in-depth here.
If she looks familiar, she also did a Merida cosplay that got floated around here, although I can't find the original post (I looked).
Anyway, I have to go sob uncontrollably because I'll never be this good at anything.