Aulendur
From Tolkien Gateway
Aulendur, "Servant of Aulë", is called one of those Noldor, who actually "entered Aulë's service, and who in return received instruction from him." Mahtan was one of them.
Source
The Peoples of Middle-earth, The Shibboleth of Fëanor, note 61 (p. 365-366).