If you actually want to damage sensors of unattended autonomous vehicles you could do a lot worse than just like...shooting at it with a firearm. Delicate precision sensors don't take to bullets too well, also using firearms lets you be well outside the range of the target vehicle's sensors.
when red light cameras came to my town, a person dressed as Santa Claus carried large wrapped boxes with holes in the bottom. The person put the packages over the cameras. AFAIK, no one was ever charged.
Maybe in the future it'll be impossible to get away with things like that in the future.