Just cut your tube to make a base like one of these, or invent your own pattern..
It closes and holds thanks to the grip of the tube. (static electricity I think)
Then ... let's decor it !!
About rexlace wrapping, see this diagram.
I begin to hold rexlace with the thumb, and i wrap it well tight.
At the end of the wrap (or of the rexlace !) I make a large loop, maintain it firmly with the thumb and pass the rexlace in it.
Then i knot it very very tight, and cut at 1-2mm.
Et voilÃ ! No glue ! :)
For the Sakura necklace, i covered the thin tube with ribbon and glued it on each ends.
I wedged a big bead (filled with hot glue!) in one of the ends of the big tube, far enough to let the thin tube enter in it, putted -washed- sand (otherwise it make tube dirty and opaque) and 6-7 paper sakuras (see pattern here) and closed the tube with another bead, far enough again.
Then i wrapped black rexlace around each end.
For the Metal necklace, i've fill up the little thin tube with water, and closed it with screws that (luckily !) fit in the tube.
I threaded a bolt on it, and (hot)glued it.
I hotglued the little bolts too.
I filled the long thin tube with fake zebra fur.
For the Steampunk one, I've filled the big tube with colored water (with green ink) and closed it with big beads which had chains on it (beads filled with hot glue again).
I screwed two big brass bolts at each end.
The thin tube is wrapped with brown ribbon, which looks like leather i think ^^'. I glued it with (a lot of !) hot glue, because there's a great tension on this part.
And the clasp is a part of big tube wrapped with 2 rexlace (orange and black).
I added little gold rounded sequins, which i cut to make it like gears.
For the Zebra necklace, my first actually, I filled the thin tube with fake zebra fur (with the help of a knitting needle and crochet :D it's a little bit hard because of the tube's grip), and wrapped the big tube with a sewed tube of fur.
Then I wrapped each end with black rexlace.