How can I project an image onto Glass?

I saw this done at a bridal show, and wish to do it at my wedding reception. The glass was sandblasted on the back and the projector showed a wedding video on it. I already own a projector. But what would the dimensions for the glass be? How thick, ect? I’m looking into a 42′ screen. Also how much would something like this cost? Thanks for all your help!