bone
Traditionally, nuts and saddles (for acoustic guitars) are made from bone. Bone is hard wearing, nice to work with and looks attractive. Other materials commonly used are brass and other metals, hardwoods and plastics.
Electric guitars usually have manufactured metal saddles, individually adjustable for height and intonation and come in numerous finishes including chrome, nickel and gold.

Each bone nut or saddle is custom made for the instrument from a blank piece of material.
uniform string spacing
slots cut, spacing and basic shaping
perfectly fitted with no movement
each string is individually intonated
saddle fitted, radioused and string positions marked before rough shaping
maple selected
blank sized
polished, height adjustment and snuggly fitted
slots are angled to prevent string bounce
final shaping, polished and fitted
break angle & minimum string contact 
improving volume, tone and sustain
old saddle and new blank
string positions intonated and final polishing
blank formed
thicknessed, radiused  and rough shaping
strung up and tested
freshly made nut
slots are angled to prevent string bounce
uniform string spacing
slots cut, spacing and basic shaping
final shaping, polished and fitted
perfectly fitted with no movement
break angle & minimum string contact 
improving volume, tone and sustain
each string is individually intonated
old saddle and new blank
saddle fitted, radioused and string positions marked before rough shaping
string positions intonated and final polishing
maple selected
blank formed
blank sized
thicknessed, radiused  and rough shaping
polished, height adjustment and snuggly fitted
strung up and tested