I've got just the thing for you!
Get
2 big zipties
A rectangular wash bucket/bin (like
this
Small carabiner or other clip (
like this)
Drill.
Modify your NIC by lifting a panel (at bunny mouth height) up about 3 grid squares on a stable wall. Just overlap that panel onto the one above/below, so the rest of your structure can maintain its dimensions.
This will leave a long rectangular opening in the NIC the width of one grid.
Drill a hole in each corner of one smaller side of the wash basin, so that you can work a ziptie through it. Visualize the wash bin as standing up like this, opening against the grids :
[
Drill a hole in the centre of the "top" side of the wash bin, large enough to work your carabiner through.
Then, ziptie the bottom of the bin onto the outside of the cage, just below your rectangular "munching" opening.
Bob's yer uncle!
One gigantic, easily refilled hay bin!
I created this for one small princess at my house who insists on dragging hay into the litter box, then proceeds to pee all over it. Never mind eating it, just pees on it
.
So far, this has worked really well
Here is my wicked MS Paint version:
View attachment Bunny hay bin.gif