Apparently you can just google "3D snowflakes" and get a whole host of tutorials. This was the first I found at WikiHow. It had so many photos I didn't bother looking further.
While I didn't make these, I think if a couple of kids can do such a LOVELY job, you and I should give it a try :0)
Wouldn't they be perfect in a classroom all across the ceiling, or maybe at your New Years Eve party? I am going to make them for my archway from the living room and leave them up all of January. It will be the most snow Phoenix has seen in years :0)