Building my own roomlens

I'm attempting this project, which should be pretty easy. I need particulars from people in the know, possibly owners of Argent's roomlens product itself. What size tube is used? Are the tubes sealed at the top and bottom? About how far apart are they? Are they "stuffed" with anything? How Tall? This wierd "Heimholz Resonator" apparently befuddles and impresses all who have experienced it properly set up. $1200 for 3 is a little much (kinda like cables), I bet a set would cost less than $50 to make. Let the information flow.... THANKS