you can make a ferret wheele,, bit like a big hamster wheele,, and they will youse it
also i think some cages are to small my presant court is 8 foot long 4 foot wide,,, and is 4 foot high,,, i think the hight is important,,my ferrets climb right up to the top all the time then slide back down,, wich keeps the nials down, they also jump of a board on to the wire,, al good stuff for keeping them fit