There has been discussion on the FML about sleep boxes and the advantage
it has to keeping sleep places dark.  I have used sleep boxes in all my
cages at the shelter almost from the inception of the shelter.  Below is
the description of the boxes I use and sell in my store, with a link to
the picture; compliments of Harry Pike so you can see what the fur kids
do to keep it dark and warm.
 
Brenda
 
Small sleep box: Made of Balsa plywood sanded to a soft finish, topped
with permanent vinyl flooring for durability and easy cleaning.  The
sleep box is 8 1/4" X 10" X 8" with a 4" opening for entry.  This sleep
box belongs to Evita and Junior, two fur kids left of a 3 group.  Notice
the blanket in the box.  I put receiving blankets or sleep sacks in all
the sleep boxes in all the cages.  The fur kids get in and stuff the
blanket or sack in front of the hole so it is all cozy and dark in there.
This box held all 3 kids with no problem, it can hold up to 4 ferrets at
one time.  Ferret tested and approved by our shelter ferrets.
 
Bradley's Sleep Box (large)
 
Made of Balsa plywood sanded to a soft finish, topped with permanent
vinyl flooring for durability and easy cleaning.  The sleep box is
10 1/4" X 11" X 7 1/2" with a 4" opening for entry.  This sleep box
belongs to Des and Ophelia.  Notice the blanket in the box.  I put
receiving blankets or sleep sacks in all the sleep boxes in all the
cages.  The fur kids get in and stuff the blanket or sack in front of
the hole so it is all cozy and dark in there.  This box will hold up
to 5 kids with no problem.  Ferret tested and approved by our shelter
ferrets.
 
Link to webpage for sleep boxes
<http://www.kwflatbed.com/brenda/sleepboxes.html>
[Posted in FML issue 5241]