Glad you liked the pics!! They just love playing in them.
Momofmany: right on the nose with the materials. Didn't feel like making them, so bought instead, and this was the best bang for the buck at $20/4 ft section. I bought mine from petdiscounters.com, and I really liked this vendor. They also sell them at Petsmart, but I would have had to pay taxes, and I think their shipping was higher. I couldn't find them for less anywhere else. I did a search for "cat tunnel".
I bought 6 segments of them, they tie to each other in different configs, and the Y segment makes it even better.
Downside: they collapse, since there's no 'ribbing' to brace it, so I get the best results tying them to something stationary. Otherwise, when they dash thru them, they drag them along, of course. Another alternative is to beg some free cardboard tubes from carpet stores that can come in diameters of 1.5-2ft and up to 14ft long. (Home Depot won't give them to you) But they're not collapsible and store-able as the tunnels.