Complex sentence: To cement that a fake head was no longer being used, white eye slits were drawn into the mask, while in the original design the eye slits were black, implying that Lonnie Machin's own eyes were now behind the mask.
Split into simpler sentences: To cement that a fake head was no longer being used, white eye slits were drawn into the mask, while in the original design the eye slits were black. This was intended to suggest that Lonnie Machin's own eyes were now behind the mask.