This is a very easy craft that doesn't take very much time to do. My 2-year-old loved this one!
All you need is contact paper (I bought a roll of it at Meijer.), some tissue paper cut into squares, and construction paper cut into hearts.
Place the construction paper heart on the sticky side of one piece of contact paper. Let the kids stick tissue paper wherever they want in the heart.
Put another piece of contact paper on top of the tissue paper (the sticky sides of the two sheets of contact paper will be touching to seal in the paper).
Cut out the heart and tape to a window.