Effectively gluing the glass to the aluminum isn't a very good long term plan. The best thing about using glass is being able to unclip and remove it. Then if you have 2 pieces exactly the same thickness you just slide a new one in, prep it with what ever adhesive, then start printing again. It all depends on what you are printing I guess. Small stuff plucks of glass pretty easily when it cools down. I have been printing large pieces with a flat solid bottom. It takes quite a bit of work to get these off the build plate and it is good to be able to slide a long flexible putty knife on all sides to gradually lift it.