you may be in some luck then as I am from rawalpindi and can help you do a test panel based on which we can decide if clay would work for you or not before you go spend big.
As far as glass is concerned, there is glass clay but I think we can use a cleanser to get rid of it. We can check with both paint clay and werkstat prime strong on glass. Glass wouldn't be much of an issue though as we can even go stronger on it without worrying too much about it compared to paint.
For rubber, we may be limited in choice as clay wont work on it and using a strong cleaner (apc) can dry it down but we can try.
Can you wait till the weekend and come over to my place on Saturday morning? I'll PM you my number.