When it comes to theferret cages there are two options: buying one or making your own ferret cages. Get a medium to large sized plastic dog or cat carrier. Get a small cat litter box (the smallest size made will fit a medium/large ferret cages), or even a plastic shoebox. Secure the litter box to the back of the ferret cages with a couple of small nuts and bolts, or by drilling holes and twist teeing it in. Get a second litter box and fill it half full with litter. Nest the second litter box in the first.
Next, get one or two sweatshirts or pairs of sweat pants - not a gross pair but preferably one you've worn maybe once and haven't washed yet. So it has a little bit of your scent on it. Either that or a clean pair. Put on the floor of the ferret cage. If you're really handy, buy or make a small ferret hammock and hang it from the slats on the top half of the carrier. If you don't do this part that's ok too.
Fasten a food dish and water dish (or a water bottle over a drip dish) to the door of the ferret cages, (or to the wall of the cage if you're up for drilling a few more holes). Once your ferret cage is set up in this way, bring it out to the ferret. Find a way to prop the door open so it can easily get in and out. Maybe use a rock so it won't swing closed. The ferret should voluntarily enter and start sleeping in this within the day. Quietly check from time to time, and when you do notice it sleeping in there (it might be buried in the sweat shirt/pants), quietly close the carrier door, and you've got yourself a ferret cage.
Ferrets are the sweetest animals, but nature is nature. Additionally, they love a challenge and almost always rise to the occasion. If you turn your back on it, it will probably get into one of those ferret cages if given the chance and might succeed when you least expect it