is the mouthpiece (where it is broken0 part of the main body of the bong? or is it a seperate piece, sealed with a rubber o-ring? cause it'll be pretty hard to repair a break on the main body of the bong...you'll never be able to melt the glass back together without shattering the bong in your hands. 2-part epoxy is your best bet...but clean it up real good, and let it air for a few days. glue fumes aren't the best thing for your brain cells...