i found the tubes in the trash, left over from fabric bolts. maybe ask a local fabric store if they have any. i was living in LA, if you live there, you can find loads of these downtown near 9th and maple.
i wrapped string around each tube, connecting it to the next one, similar to bamboo mats. i wish i had step-by-step pics, but i don't. if i remember correctly each shelf is 5 tubes deep.
next i painted them with leftoever green house paint with watery blue acryllic on top, to give it more of a bamboo effect. the housepaint helped solidify the twine so the tubes didn't rotate in the string.
finally i drilled some holes in the ends and hung it from ceiling rafters.
i eventually sold this on craigslist when we moved...maybe i'll see it online somewhere else.
it held up really well. those books were really heavy.
here's the large image on flickr: http://farm1.static.flickr.com/41/79174121_cb5c9cac29_b.jpg