Orizomegami

The Setup: Iron a few coffee filters to make them flat. (An adult’s job—iron up to four at a time on the highest setting, no steam.) Set them out on a covered surface with lots of paper towels and a few bowls of liquid watercolor paint. (We used Sargent Art Watercolor Magic, $11; amazon.com.) You can also make it from cake watercolors: Remove each one and place in a bowl, then add a few drops of water at a time, mixing as you go, until the paint becomes a thin liquid.
Fold the Coffee Filters: Show your child these techniques to start— then encourage her to experiment on her own! FOR STRIPED DESIGNS Accordion-fold the coffee filter in 1-inch segments to get one long rectangle. Then accordion-fold the rectangle in ¾-inch segments to get a small rectangle. FOR CIRCULAR DESIGNS Fold the coffee filter in half three times so you have a cone shape. Unfold into a half-circle, then use the creases as a guide to accordion-fold the filter along its radius, like a fan, until you get a skinny triangle. Fold one corner of the rounded edge down to meet the opposite long edge, forming a triangle. Then accordion-fold the paper two more times, matching the corners to long edges, to get a small trapezoid.
Add Color: Dip a corner into the paint very quickly. Repeat with other corners, using new colors. Press the wet filter between two paper towels to squeeze off excess liquid, then gently unfold it and set on a protected surface to dry.
Bonus Fun: Play with other porous materials (such as tissue paper, newspaper, or fabric) to see how the paint absorbs with each.

(I found it here)