Leggo Building Blocks

I built a bong for smoking on Leggos. I collect various types of pipes, bongs, and hookahs, and thought a water pipe made out of Leggo blocks would be an interesting novelty. I finished it, but when I fill it with water leaks quickly. And it is not airtight at all. I wondered what I could do to seal it so water / airtight while leaving it safe to smoke out.

Can you put a container in and around the container? Maybe a glass or a vase?

Silicone, it would be tight, but I would not smoke out of it. It is probably toxic when used like that.