for my first homemade bong i used a 1 litre bottle of vault and cut a hole in the side of it. then i got a thick pen tube and taped a thin pen tube to that to make the downstem really long. then i put a small hole in some ductape and put the downstem through that and taped it to thebottle. then i found the biggest metal pen cap i could find and use that as the bowl. well thats just what i did, and it worked pretty well. happy toking