I'm baffled! Lol
I think plant pots would be a good idea.
This is the person that has inspired me to do some painting on glass - http://www.facebook.com/Pilfered1?ref=ts I have asked her for advice but she hasn't responded so I'm guessing she doesn't want to give away her secrets (if they are secrets!)
I know some of her things aren't glass so I wonder if she's using the same thing.