There are a lot of different possibilities! A classic favorite of mine is making pinwheels - both fun objects for kids and adults to enjoy!
Along with pinwheels by themselves as a decoration, try attaching them DIRECTLY onto the invitation for a festive look! Using a long envelope so that I could adhere the entire length of the pinwheel, I adjusted it at a slight angle onto the card.
I adhered additional papers as the background, and stamped the words, 'celebrate' in a repeated fashion. I accessorized my card with buttons, twine, and pearl gems. Added some dimension for the buttons with adhesive foam.
These are something that could be done very quickly - not time consuming at all - keep them small to mid-sized and you can whip out a ton of them fairly easy.
Stamps: Everyday Sayings by Lizzie Anne Designs.
Papers: Cream cardstock and Stars and Stripes Digi Papers from Lizzie Anne Designs.
Buttons: Making Memories.
EK Success punches.