We used coffee filters to first cut out snowflakes (Eric's and my contribution) and then had Z use water colors to enhance them. We had them taped to cardstock, so you can see in the third image here what a successful "background" looked like. The Artful Parent was our source of ideas for this one.
We used painters tape on cardstock, painted with winter colors and then peeled off the tape. Check out the instructions at Frugal Family Fun.