"seems to be similar" probably isn't good enough. Few things stretch as well, and launch a projectile as well, as surgical rubber tubing. When Mythbusters did some testing, it outperformed commercial and "military spec" bungee.C-A_99 wrote:some exercise stretching band that seems to be similar to surgical tubing
On lethality, that's as much a function of dimensions as of the material used.
Now I think about it, I'm not sure an actual bow is a good idea for launching water balloons. They tend to accelerate the projectile over quite a short distance; in an ordinary bow, the arrow reaches full speed (which might be 150 or even 200 mph) in about its own length. That seems like it would break a water balloon. A slingshot would I think accelerate the balloon more slowly.