No matter how big a ferret cage is, most ferrets want to get out of it lol
I know someone's ferret that is always making noise to play outside the cage (its a ferret mention)
My ferrets only have a small one-flored cage but its always open because they have their own ferret-proofed room.
So all the toys and tunnels are all around the room, they go in the cage only to sleep, eat and to go in the litter box.
However its good to have a big cage like ferret mention if you can't have them a room
Anyhow I will upgrade the cage soon because I want to put more hammocks in it