Have you ever gone to a friends house and their bong broke? Downstem and bowl are pristine but the glass that goes with it is shot to shit? This has happened to me probably a handful of times, but all of those times, I've wanted a quick fix. I carved out the top of a PurAqua bottle cap and put in a rubber electrical grommet. Most downstems are half inch, so it should fit snug and tight. after you fill it with water, make a hole for a straw or tube, seal that bitch up and you have a quick bubbler.