This video shows how the maker of that Monster Tubulum actually put it together. Between this, the FAQ on his blog, and a whole lot of intelligence, you'll have all the information and insight you need to put together your own super awesome PVC instruments.
Stand back, music world! There is an onslaught of high-brow precussion headed your way, and I have a feeling that music as we know it is about to evolve. Wait till you see this mixed with Ableton, live and loud. WOMP! WOMP!