We tried making Puddle Jumpers (Wolf Elective 7B) tonight. They were easy and both my Wolf cub and Sprout enjoyed playing with them. All you need is 2 of the same sized cans (we use larger cans to counteract any clumbsiness... large fruit cocktail) and some cord. Poke holes in the cans with a can opener, string the cord through and viola! Instant entertainment.
Puddle Jumpers are an easy elective to get done and actually keep the boys entertained for a few hours.