get a nice bottle, and yes you need a carb so you can clear the chamber better. id would say the best thing used for making a cone is a socket from a ratchet set, number 10 or 9 or 8 works best then get some hose pipe about 10cm long, then wedge the socket in hose pipe not fully in but enough so its tight, now you have yourself a cone.. then make a hole using a lighter in the bottle and put the pipe in the bottle and make another hole for carb. and there you have a homemade bong..