Arcane University:Niftools/Chunkmerge for Skyrim

Nifskope/Niftools is a very important tool as it allows adjusting and modifying meshes outside of full 3d programmes in nearly the same rendering as in game.

http://niftools.sourceforge.net/wiki/NifSkope

Chunkmerge is a community standard to add collision meshes to a nif but it does have its limitations for specific mesh types.

grab it while its hot!