Short term, kids could weave colored fabric
bubble refills, great idea for an outside birthday party
Collect rocks, pebbles and stones on your next trip to park and beach. Make hand painted rocks, rock painting, painted pebbles, painted stones & stone art.
32 Fun DIY Backyard Games To Play (for kids & adults!) this has some of the best outdoor ideas I've ever seen. Will be trying ladder bean bag toss and sidewalk/box board game