I tried today with a rubber ball(in our terrace one can find a ball in a week) , cut that with a shart knife and made a small hole using the welding gun (all in 30 sec hehe) tried in all cars in workshop , nothing worked out! , in a santro what we got is a dent!
with so many cars around , and so many balls in our terrace , though i knew it wont work , we did just try.
another reason - exactly on same day a car was locked inside with its key in , and was supposed ready for delivary.
Before trying our normal method , we did try this ball method.
Hope there is nothing wrong in giving a try!
Hold on , On explaining this , my tinker accepted , that a air can open up the lock - only on a particular direction and its 100% impossible to attain in that direction , no matter you own a compressor.