Would it be poosible for a parent to donate an extra snack a day?
In the winter, I make penguins out of oreo cookies. I buy the oreos and candy corn. I have another parent donate white frosting. And I have a second parent bring in M&Ms for the eyes. **Ask for these donations the day BEFORE the craft, in case they forget...
Do a search-- "edible summer preschool foods"
Sometimes it's just fun to make a "face" on a paper plate---Olives for eyes, sliced carrots to form a mouth, broccoli for ears, etc...Or a fruit face. I would rec using cream cheese to keep the food pcs from rolling !
Do you have a juicer? It's fun to juice watermelon.
Oriental trading has a few nice sticker scenes that be purchased on a budget if you need a time filler.
Perpetualpreschool.com has good ideas by theme.