Our current favorite are those little foam stickers. Relatively cheap for hours of fun (if you are OK with picking up hundreds of tiny pieces of backing. ) M loves the foam (for some reason only the circles and hearts these days) and will happily stick for 20 minutes at a time. Set them up at the kitchen table with a little music, involve them in cooking when you can. We combined Valentine's present making by getting some cheap (sorry Gramma and Grampa) picture frames and having her stick colorful borders. (Ikea, Walgreens,Target dollar aisle have decent cheap frames.) Stick on hearts, and mail to the Grandparents!
from Michaels for $6.