For the downstem you could just drill a hole like frozenhits did, then put the glass downstem in and use snow to seal the hole. You don't have to worry about it getting too hot too fast because the slide won't even get that warm at all.
I would be more concerned about freezing my glass then taking it out and having a flame anywhere near it. Where as my method would be the same result but less risk to your glass.
You should try make, like a 3 foot ice bong, which a stand and shit... and like some dude said, try mix some color into the water, would be awesome ... Also im thinkin, maybe demineralised water will make the bong more transparent? Anyway, awesome job on the video, i really enjoyed it !
That's the beauty of technology you can use a freezer and get the same thing us Northeners have to deal with for 6/7 months of the year. Fuck winter >,<
Sweet, dude! I'm gonna try this soon. I've got an extra freezer out in the garage that's just begging to be used for this.