I haven't set up a sticky window in a long time and Miss Independent has been really interested in using our tissue squares. Sticky windows involve cutting a piece of paper from a roll of contact paper and then using tape to adhere the paper to the window with the sticky side facing outward.
When I had a great coupon I purchased tissue squares from Michael's, but you can make your own too.
I leave the squares in a bowl by the window for a week or so. It is really pretty when the light shines through and you have lots of color on the window.