This is a "fun" activity I did a few times in first grade back before the Common Core sucked all the fun out of first grade. I would even hang them on the classroom windows before the fire department sucked all the fun out of that. But it works well as an at-home activity where we can still have fun and still hang things on our windows.
I gave M only blue and purple paint for this because if I didn't we would have brown snowflakes. An old ice cube tray worked well for holding the paint.
I cut out some snowflakes for us and M painted them.
If we had coffee filters they would have sucked up the watercolor and allowed it to spread, making some cool designs and more evenly colored flakes. Like I said though, this worked too.
I also used to do something similar to this for Earth Day with coffee filters and blue and green watercolors. It makes a very neat looking swirly Earth. If you don't have watercolors on hand you can also try washable markers on the coffee filters then use a spray bottles to wet the filter, the colors should spread.