We use to buy beer online from Woolies delivered to your door when we were under aged.

When they came to the door we would say "oh that must be for dad, he just got in the shower, if you wait for 10mins he will be out????,,,,or I can just sign it for you".
The 17 year old pimple faced driver never queried it.
What Im getting at is if teens want paint, beers,what ever,,,,their is always a way.
You wont stop them geting it, better off teaching them to be responsable with what they are doing than to try and stop access as this just adds to the excitment .