Redline Acoustics builds custom resophonic guitars, mandolins, guitars, and electric mini banjos in Hendersonville just outside Nashville, Tennessee. They have been making parts for Luthiers since 1998 and carry a line of stock parts for Mandolins, Banjos, Dobros, and Guitars. They also specialize in custom work.
Source: RedLine Acoustics website (5 June 2019)