String bubbles - 2 straws and 1 piece of yarn - string yarn through both straws, tie a knot, then rearrange into a square. Can do bubble 'windows' or use it to blow large bubbles. Get hand wet w/bubble solution and you can stick your hand through it.
this one sounds even easier to make: bubble snakes = easy quick craft. Cut the bottom off water bottle. Put old sock over bottom and duct tape. Add food coloring for fun. Dip end in dish soap mixed with a little water