Complex sentence: Subsequently, the designers were able to develop a new cowl, first used in episode eight, that easily slid over Gustin's face and locked into place, allowing him to get into the costume in approximately 15 minutes.
Split into simpler sentences: Subsequently, the designers were able to develop a new cowl by episode eight that easily slid over Gustin's face and locked into place. This allowed him to get into the costume in approximately 15 minutes.