Guests throw darts at balloons with paint inside. You keep the art. :) This is such a fun Idea. You choose the colors and the size to coordinate with your style - might be more enduring than having a fingerprint tree in your house forever.
31 Impossibly Fun Wedding Ideas: instead of a kids table include a small bucket of crayons and coloring books on each table, with a sign that says "for kids and adults who love to color". Or something similar to that phrase:) kids area, let them be free!
Dramatic stacked wood stump backdrop for wedding ceremony altar. Maybe instead of an arbor, the wood stumps could define the ceremony area. We couldn't use candles but led lights if twilight for soft glow