Hey
Recently the PS3 game Natsuiro High School got released, and despite its rather rediculous concept and uninteresting looking gameplay it does have some nice 3D models, especially for the environments.
The game came packaged in a CPK file, which I extracted into around 20 subfolders, 2d, 3d, bg, ui etc.
All the folders regardless of their content seem to contain files with the .cat extension, after poking about in hex it looks to be an archive, but it doesn't appear to be compressed.
The Field folder is full of tmd2, I remember PS1 used .TMD for its 3D models in quite a few games, outside of this theres the occasional lyd file, they're always rather large so I assume this contains 3D Model data too, same as the other 2 formats, but Its still just a guess.
I've uploaded some file samples to dropbox here for anyone who might be interested to take a look at.
I can't say how complicated it is though, I'm still learning how to make my own QuickBMS and its early days yet.
Thanks