i've done them and i'd be more worried about how harsh they make even the kindest weed than the long term effects....there are countless things you can use...just use your imagination.....just whatever you use make sure it's all air tight and the metal you use for the bowl is safe.....ie. don't use aluminum or copper....those two i know for sure have some kind of bad that comes with them....brass would be the ideal metal to use for a bowl next to steel and stuff like that....electircal tape and hot glue will become your best friend while making bongs....hotglue dries quick with no harmful and unwanted vapors (like super glue would have) and electiral tape is an air tight tape that is flexible and stretchable which is a huge bonus....look through some old posts to get an idea of what you might wanna do...the main thing i feel i always have to express to people just now getting into making things is that it doesn't have to look like anything else you or anyone else has ever seen, it don't even have to be pretty (although it does make you feel alot better about your creation when it looks nice, clean, and menacing) all that matters is that you enjoy smoking out of it...it's not too wasteful on weed, and it actually does work like it should.....good luck dude and happy toking