Tutorial: Exporting skinned skeletal meshes from Blender to UDK as PSK/PSA

or, "Did I really just spend the last two days on this?"

I've been working on this riddle for twelve hours now (thanks for nothing, google) but I finally managed to get my rigged, animated model into UDK. I'm putting it here because eventually it's going to come up again when I've forgotten the process, and to spare any poor souls all the anguish it's caused me.

so, without further ado,

"Exporting skinned skeletal meshes from Blender (2.68) to UDK as PSK/PSA"

What I noticed is that edge splits and armatures can both be exported, but not the same time. The trick is to export the mesh and animation separately, with different settings applied.

Export mesh (psk) only:

• With appropriate edges marked as sharp (but no edge split modifier applied).
• WITHOUT an armature modifier applied (very important!)
• "Smooth groups" is checked in the PSK export options.
• DO NOT check  'rebuild on export' in the export options.
• If you can hit "check mesh vertices" and the duplicated model looks normal (not deformed) you're good to go.

Export animation (psa) only:

• WITH an armature modifier applied.
• DO check  rebuild on 'export' in the export options.
• Doesn't matter if your edges are sharp or not.

Other notes:

• Make sure you have at least one material applied to your mesh, or else the exporter will throw an error. 
• UDK will import separate material channels for each texture on your object in Blender.
• DO NOT try to export either psa or psk with a mesh split modifier- it will crash Blender.
• The FBX exporter is a million times easier than this and works fine for both static meshes and rigid-skinned animations, but does not like to work with paint weights that are set anywhere between 0 and 1, so it's not suitable for organic animations like humans or animals.

Good grief, this would've taken 30 seconds to do in Unity.