I use a separate, small cage for time-outs.  No hammocks, no toys, just a
sleep blanket & food & water.  Confinement to the time-out cage (called
the "Penalty Box" around here) is usually for behavior naughty enough to
deserve eye-to-eye (in your face) scruffing and scolding or scruffing and a
short drag by the scruff over the carpet before being placed in the cage.
Like you, Chris, I wanted to be certain they do not associate their cage
(or their pet taxi) with punishment.
 
I have quite a few ferrets who run free during the day (yes, constantly
supervised & continually ferret-proofing) but are caged at night or when I
have to leave the house.  Several of them seek their "nite cage" for naps
and when bedtime approaches.
 
Debi Christy
[Posted in FML issue 2946]