Here’s an idea I got from The Tightwad Gazette by Amy Dacyczn. Keep the lids to concentrated frozen juice. Put matching stickers on to make a memory game for kids. You could also paint or draw shapes, letters, colors or whatever to help them learn. And you can keep adding to the game as you collect more juice lids (as you can see I need to save more.)
You could do this with card stock paper too, but the juice lids will last a lot longer. And they stack really nicely! Plus frozen juice is a lot of times cheaper than bottled. Check the ingredients in bottled juice, a lot of them are made from concentrate.
This is a great frugal gift idea for kids. You can personalize them by using stickers of one of their favorite characters, then tie with a pretty ribbon.