Safe downtube for my GB invention

Hey there,
In my neverending quest to get as blowed as possible, a close like-minded companion of mine and I have invented a new device that blows away any bong or pipe we've ever hit (same goes for anyone that's tried it). It is a spin-off of a gravity bong. It is similar to the Blisset Bucket, though it has many many improvements over this design.
We plan to patent it as soon as we have a viable prototype. Currently we have one in use (out back in the treehouse for serenity), but we do not wish to just make a bunch of gravity bongs and sell them. We would like a professional product, with an enclosed top to prevent spills and very uniform parts. I have located almost all of the parts we will need, taking into consideration the dangers of PVC when burned.

Now to my question: We still have not located the downtube (female piece) for the device. It will need to be almost a foot and a half long, making glass impractical. It will have to be able to have very small holes drilled into it, and it must not release fumes at fairly high temperature (right underneath the bowl). The most important part is that it needs to be clear (don't you just love watching 3 liters of smoke pour through this tube and bubbly bubble up into the chamber?).
I was wondering if acrylic tube meets these requirements, though I doubt that it does considering acrylic bongs sold at head shops all have a metal downtube. I did not want to go with metal since it is not clear.

When we are done with the product, we are considering attaching a magnifying glass to the top on a swivel for solar puffing this humongous and very smooth hit.
I would highly recommend going out and building yourselves a Blisset Bucket (especially if you're in an area where high-grade is hard to come by, though high grade is especially gratifying in the device) and you'll get an idea of how this amazing contraption works.

Thank you. I hope some of you knowledgeable potheads out there has a solution for me.

Stoned Wheat Thin

Why not use plastic tubing attached to a stainless steel downpipe.

Like the tubing that is used for most fish tanks?

Ooh I guess we hadn't thought of something like that. I may choose to use 1/4" acrylic tubing about 6" down to prevent heat transfer.
Any ideas on where to get the metal pieces to make a standard tube for a sliding bowl? i.e. an upside down cone on top of the tube.
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Ooh I guess we hadn't thought of something like that. I may choose to use 1/4" acrylic tubing about 6" down to prevent heat transfer.
Any ideas on where to get the metal pieces to make a standard tube for a sliding bowl? i.e. an upside down cone on top of the tube.

This thing right here

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Any mouthpiece for an instrument....trumpet trombone tuba socket or go to a head shop and buy a slider for a bong.

wow i never thought of the mouthpiece..
I was thinking more along the lines of maybe those metal tube pieces that the small metal pipes are made of. you know -- the ones that unscrew to like 10 pieces so you can clean them. I was thinking maybe one of these pot heads would know where to buy the individual pieces that those pipes are made of.
This will be a bulk project, and it would look pretty silly to headshops if I went in with a bong for sale to them and I had to buy sliders for each one before they would buy the bongs from me ??!!
Thank you for your suggestions. They are giving me many ideas.
When the product is released I'll be sure to let you know

Well, if you are serious about it just go to a tool and die company and have them mill you a downtube with a bowl on top.

Yes I guess so. I just wasn't looking to have to actually design any of the parts myself. I know the pieces are out there for sale, I am just trying to find them.