Simple double gatorade bottle bong, turned out really well.

Here's the picture

We made this out of two gatorade bottles, cut off the bottom of one, and the top of the other, then superglued and taped them together. Then we used a door stopper with a pen that handily screwed onto the door stopper, and we poked holes in the bottom of the pen for a diffuser. We also made a removable extender piece for the top, and put some glow in the dark airsoft bbs in the water for some extra diffusion. Hope you like it!