Collisions in 3ds max for Skyrim
Using as few programs as possible when adding custom meshes is preferable to many people, including myself, this tutorial shows you how to add convex collision to simple objects in 3ds max and how they are exported and cleaned in nifskope.
Convex collisions are great for simple objects and objects that you would like to move around, ie kick around, grab. all with collision.
Convex collisions will absolutely not work for architectural and complex objects, for that you need to watch my video on ChunkMerge.
Thanks to the Niftools team, Wix and TheFigment for their 3ds max exporters, which can be found here at the nexus and the niftools forum. The Wix's exporter is slightly newer.