Minox themselves still supply a small selection of sub-miniature films http://www.payworxx.de/minox/index.p...udqsa5dgf2sv44 ); I believe they cut and pack this themselves from bulk film from one or other of the main manufacturers, and that a few other specialist suppliers also supply reloads.

But I'm not aware of any "film factory" actually making special emulsions or finished films for Minox or any other sub-miniature formats, the demand would be minimal.