I tried to create a new model using 3ds max but that didn't work. So i decided that it would be easier to just edit the chinese stealth armour so that i wouldn't have to scale it or animate it.
Can someone tell me what programs i would need to do this and what steps i would have to follow to edit an already existing Fo3 model?

Okay, thanks, i got blender an nifskope, but to get the scripts to import and export NIF files, i had to get python and pyffi. Where do i have to install them to get them to work?

Well you'd need NifSkope and the various NifScripts to import/export nifs in your modeling program of choice (at least I think it works for non-blender stuff... maybe you have to use blender) first of all. Then there are some tutorials on how to add/create armor in a 3D program and get them into the game on the Oblivion Wiki but the links escape me and it's all over my head anyways. I'd try that first until someone more knowledgeable comes along.