Complex sentence: Kutten were primarily made from denim jackets with their arms removed or cut very short; in the case of many-pocketed jackets often some were cut away to gain more space for the patches.
Split into simpler sentences: Kutten were primarily made from denim jackets, with their arms removed or cut very short. In the case of many-pocketed jackets, sometimes pockets have been cut away to gain more space for the patches.