Nautigal - that site is awesome :-) That is where he found the plans for his small size that we just finished and are quite giddy with using a variety of small cat toys that are zooming through our house as I type...I smiled with kimck's comment because he was the one who found the cat toys and thought they would work perfectly as projectiles and then I read your post
:-) He is already planning how to make the mechanism stronger with better bands or bungee cords - oh my is all I can say!