You live in the land of bamboo man...Make your own.
Excellent observation.
I've always wanted to make my own wooden/natural material piece, so congrats on trying.
This is what I would do if I where you. Hopefully your bamboo is at least 2 inches thick or so and hollow, otherwise it might make a better steamroller, but here we go. Your going to want to cap one end off. For that you could either cut a piece of wood and sand it carefully into the shape of the hole at either end, or you can just have it overlap the bottom and sort of make a base for the whole thing to stand on.
What I use as adhesive in all my bong making is JB weld
http://www.giantleaprocketry.com/images/JBWeld.jpg.
I use JB Weld because anything else you use can heat up and release chemicals that might be really bad for you. Most glues out there are not made to withstand heat and flame, but JB Weld is actually strong enough to hold metals together (for example: a small crack in the water jacket on your engine block). Not that I've done research or anything, but I'm like 99% sure JB Weld is a safe adhesive for bongs, definitely more so than any silicone adhesive.
A silicone adhesive works wonders for water retention, but worries me when theres heat and lungs inhaling smoke involved. Anyway, so you got your end capped off somehow, now you basically just need to make a down stem.
Since you have bamboo and are probably going for the natural look I would use a wooden dowel. Measure about 6 to 9 inches of dowel depending on the height of your bong. A 1 inch diameter dowel should do good, then your going to want to get some vice grips or something to hold it down while you try to somehow drill through the dowel straight enough so that you don't drill right out the side. I would use a half inch bit. The length of your stem will probably be limited by the length of your drill bit, unless you have access to a drill press which would make everything a lot easier. If you need it longer you could always make two shorter ones and glue them together.
Once you have a down stem you need a bowl. I would recommend buying a cheap ratchet head at hardware store because they only cost like 3 bucks at the most and make a perfect little bowl. Glue that to your stem, drill a hole in the side of your bamboo (pay careful attention to location of your hole, this could fuck EVERYTHING over if it's too high or low), stick your stem in the hole and seal that with more JB Weld.
Let everything dry at least 24 hours probably a couple of days and viola your very own handmade nature bong.
Of course the best part about making your own bong is being creative and seeing what works and what doesn't. I encourage you to try your own ideas and play around. It definitely adds a whole new creative aspect to smoking ganja.
Best of luck, I hope you put that bamboo to good use. I've made a lot of bongs in my day, but never a completely wooden one!
My only comment on this excellent set of directions is, speaking purely from memory, remember about the taste and smell of
It is amplified in a wooden or bamboo (naturally porus material) tool.
The first bong I ever saw was a good 4 feet long. Took a lot of huffin and puffin...but it worked.
