Lowes and Home Depot both have the green mesh.

I was at Home Depot last night and picked up a 3 x 15 ft roll of black plastic mesh for around $11.00.

I simply snipped off the sharp ends as close to the wire as possible.  With all the zip ties and twist ties the wire is flush with the cage bars anyway.

Thanks for the measurements that was very helpful! I just have one question though. Once you put on the hardware cloth how long should you keep it on? I'm getting baby boys and I was wondering how long I need to leave the cloth on.

Wow, those cages look really nice when you decorate them.
I wonder if I should write the measurements down now, so that when I move out and get my own I won't have to do the dirty work 
Or maybe when that time comes, they'll already have come out with the Rat Nation?

I've got a question about the FN cage, when you put a rat in the top, is there any way to go down to the second floor from there? In otherwords, is it one big cage, or seperated sections?

Oh I seee... Is the floor made of wire?

And is there a open spot in the pan so that you can have the pan there and the ramp down? Or does it cover the door?

Finally found this!  Thanks a ton for the measurements!  I think I'm going to need to modify my cage after all. Mika seems to be able to get out. She hasn't as of yet, but she keeps getting half way out, and then going back in because she's too scared to go all the way. So, I'm going to have to mod the cage this week. >.<

This thread really should be stickied/pinned. XD

Mine has been modded now, too!  I have lots of cuts on my hands, and sores, and a blister that's killing me today, but it was worth it!
I ended up buying 7 rolls, because I did the shelfs under the pans, too.

(Edit.)

Is the length or height first?

I don't have a Ferret Nation yet, but I would like to have it all cut and ready when it gets here so I can put it together and modify it. And For the sides, what sides are we talking about, and what about the backs? Do you consider the whole back of the 142 model 2 backs, since it could be split? Sorry, I'm just confused and I want to have it right.

Wouldn't you have to make sure to cover the "floors" as well, under the pans?  That would probably be the same measurements as the "top", right?

The measurements and the amount of supplies you gave us is enough to cover the entire 142 FN, right?

I bought a Ferret Nation 2 days ago, and found that my hairless girl Lily could fit her head and shoulders through the bars, so-o-o-o...off to Lowes I went for hardware cloth!  I also bought just the galvanized, as I plan on taking it off once she gets big enough.  For anyone else who is interested, at Lowes, these rolls are in the garden department outside.  I've gotta say, even though it was GREAT having the measurements, the whole project has been one giant pain!  My hands are shredded and fingertips almost raw from zip tying...I went through 300 already, and still need to secure both sides and the back of the top level!  It's frustrating because I am SO CLOSE to being done but I have to work tomorrow so will have to wait to go buy more zip ties. I have the girls in the bottom section only, and I can't wait till they can use the whole cage.  Like anything else, I learned along the way, and in time I am going to go back and re-do some of the panels; for instance, I didn't like having the zip ties over the door frames as it makes opening and closing more difficult...I trimmed the top level door panels a bit differently and was a