I made a hammock- very easy.  Use a small towel (hand towel), get some
material from the fabric store that is used for Christmas decorations (the
fuzzy top of Santa's boot) and cut a square of it.  Sew it into the middle of
the towel.  Make buttonholes in each corner of the towel, or just cut slits.
 Hang it from the top of the cage or wherever they can climb into it  using
plastic bag thingies (those yellow things that you clamp off the top of the
garbage bag with-not the wire ones), going through the button holes (2 in
each corner) and attaching to the roof of the cage.  Mine loved to sleep
right in the middle, and she "dug" the towel each night when she climbed in.
 It is, of course, very washable and easy to install.
[Posted in FML issue 1033]