VERY challenging puzzle. Its symmetrical both vertically and horizontally. From there just keep in mind what a snowflake LOOKS like and with some trial and error you should be able to figure it out! I had a GREAT time completing this one...mostly b/c it WASN'T completely logical and I had to work my brain to come to my "educated guesses!" Fantastic snowflake rewards you at the end! Thanks so much! ~:)
HINTS: The hint by Drceit has a small error (typo?). The very top row and very bottom HORIZONTAL rows across should be as follows: 1, 3, 5, 9, 11, 13, 15, 17, 21, 23, 25 Since it's symmetrical the very first and very last VERTICAL lines are the same: 1, 3, 5, 9, 11, 13, 15, 17, 21, 23, 25 You will also make a big "X" from the middle.