Call the Cub Club (262-966-7627) and talk to Joel. They did an article recently on a PA-12 bungee tool that his father Bob made. They are really nice people and would probably be hapy to help you out. As a last resort, they probably have plans and you could make one.
In the members area here at Supercub.org there are two bungee tool descriptions to include photos etc. They are in the section called Tech Articles & Forms. If I recall correctly at least one of these guys was willing to loan his tool - but I may be wrong. I guess this is yet another reason to pony up at least ten bucks for membership.
Not trying to rag on anybody but availability of info like this is why we support Steve and this site. Just my 2 cents.