Aren't those cards the coolest thing ever? I think so. The snowflakes were poked into a thin acrylic sheet and then lit with a LED. The cards were a great school project; lessons in rotational symmetry, measurement and electric circuits all rolled into one. You'll find the tutorial here.
I know the kids really enjoyed making these. Despite the fact that they each had to bring in $3.00 to cover the costs of the acrylic, the battery and the LED, my students are already asking if we can make them again next year.