Ku-Klip is the tinsmith who made the Tin Woodman the sparkling person that he is today. Because of the fairy magic that makes all the people in Oz immortal, there is no need for medicine or surgery. Instead, you call the local handyman to fix whatever ails you.
So when Nick Chopper began cutting off his own limbs (thanks to a cursed ax), he turned to his local tinsmith to replace his parts. Who did a very good job, all things considered.