Complex sentence: Various contributors were occasionally called in to play instruments, such as guitarist James Stevenson, bassist Pete Briquette, the band FTV (on "Black Steel") and even Saunders contributed guitar, with the resulting improvisations treated as samples.
Split into simpler sentences: Various contributors were occasionally called in to play instruments, such as guitarist James Stevenson, bassist Pete Briquette, the band FTV (on "Black Steel"). The producer Saunders contributed guitar himself, with the resulting improvisations treated as samples.