Keyboard instruments such as harpsichords, clavichords, dulcimers and virginals were played. Warner also designed and produced solid body rehearsal harpsichords and dulcimers. Modern pianos use threaded pins, as do many harps, psaltries, dulcimers, zithers, and other instruments. As a folk instrument, wide variation exists in Appalachian dulcimers. The most common type is the electric Appalachian dulcimer, but electric hammered dulcimers also exist. Cook built his first dulcimer in 1979, and has gone on to build hammered dulcimers. On his 2016 album "Rehab Reunion" he played mountain dulcimers made by BlueLion. Massengill owns and plays dulcimers carved by Edsel Martin (1927-1999) from North Carolina. In addition to vocals, Mullins performed on the lap and hammered dulcimers. Guitars and dulcimers are frequently allowed in sessions without strict "'traditional' instruments only" rules.