Seven-string guitar string is augmented with a high octave string. Many of McGuinn's notable guitar solos utilize the G string of the twelve-string guitar to perform the main melody, and therefore the Martin seven-string guitar was designed to achieve this extended range playing without the need for doubling all six of the guitar's strings. In 2010, Inox Guitars has created a mix of the Brazilian Viola caipira and the Russian semistrunka (семиструнка). This instrument has 2 bass strings (as the 6th and 7th strings of the semistrunka) and five treble courses (as the Viola caipira) and it is used in open tuning
Fingerboard McLaughlin played with Shakti, along with Indian violinist L. Shankar, using an acoustic guitar with a fully scalloped fretboard. McLaughlin explained that this feature increased the ease and range of string bends by eliminating friction between finger and fretboard. The scalloped fretboard also facilitates the rapid, microtonal variation that is important in Indian music, as exemplified by classical Indian Sitar music. Without scallops, the guitarist must play microtones by sliding the string sideways on the fret. Experimental luthier Yuri Landman made an electric guitar for John Schmersal of Enon called the Twister with a partial scalloped neck for only the