The only problem with the paper towel tubes is that the bunny can still chew through them and get at your cords.

You can always go to the plumbing section of your local hardware store and buy the exact length of plumbing tubing you needs (it comes in different diameters so you can buy the tubing according to how many cords you have to stuff in it). Then have an adult cut it lengthwise and tuck in the wires. It takes rabbits years to chew through that thick plastic and it's fairly inexpensive....I think I paid sixteen cents a foot. Plus it's much easier to do that instead of having to replace the cords to your telephone, tv and computers.