Bunny packing boxes

Not boxes to pack bunnies in, but packing boxes for bunny playtime.
Recently, we received too much packing material, which included 2 boxes (see The Paper Box Revisited). This is a good thing because if you don't find things for your bunny to explore and chew, they will do it without you. (And how many of us have "rounded corners" on our wooden floor molding?)

Step 1 is always the same - peel off any tape, labels and staples.
Step 2 is to make some doors.
More than one helps them feel like they can escape danger.
Usually, they get at least one per side.
Some bunny slaves prefer to cut openings, but I've found
that they like to chin and chew on the doors, too.
You could stop here and the buns would have fun with this.

But since we had these great boxes,
including this huge one, we kept going.
The brown box in the first picture is inside this even bigger box.
The white box is over twice the height of the brown box.
So they have three levels to play on
and different places to hide inside.
The "doors" of the brown box ended up
holding it in place inside the bigger white box.

Lucy: Hey, there's an echo in here!
In here! ...
In here! ...

Bunya's peering down into the "box canyon".
Ethel hops from the top of the "warren" to the top
of the new box(es). She is too fast for a focused picture.
Almost all the pictures are taken without a flash and
this bunny blur is the downside. The upside is that the there is
no flash to disturb them and the colors are more natural.
And no bunny red-eye.

Ethel loves the high ground.
But she's happy to share with Bunya.

How do you keep your bunny entertained?
Please share in the comments any ideas for enhancing one's bunny playground.