[pyaranderson]

How can I make a biodegradable adhesive in a paintball-like form-factor that's durable but would break if thrown.
Scenario:  you're riding your bike.  A car cuts you off.  You have a little hopper full of these balls and have the presence of mind to get one out and throw it at the car.  It sticks to the car.  When the driver gets home, he sees it.  Inside of the clear adhesive is a laminated piece of paper or something durable with a link written on it.  The driver goes to the website and reads instructions about how to be a better bike-friendly driver.  They wash the adhesive off with no damage done to the car.  They become more conscientious drivers.

[macman104]

I don't think that in your backyard or garage you're going to be able to make a biodegradable adhesive that has the strength to stay attached to a car.  Even more, you're not going to be pressing and firmly adhering the ball to the surface, but hoping that you can throw with enough accuracy and strength to cause it to stick.  Also, spheres have very little surface area to attach something to, unless they flatten out.

Cool idea, but I don't think there's much feasibility in it.