Orbra Wallace "App" Appleton (1902 - 1994) was a musician and inventor, who reputedly made the first solid bodied electric guitar in 1941. Appleton showed his design to Gibson in 1943 but they did not take up his idea at the time. The 1941 App guitar had a single cutaway solid pine body (remarkably similar to the later Les Paul design) combined with an unfinished Gibson neck and single pickup. This first model even had fine-tuners on the tailpiece. This APP guitar was displayed in the Country Music Hall of Fame in Nashville. Appleton ran a music store in Burlington, Iowa and claimed that salesmen for the major guitar makers had come by his store and seen his invention before coming out with their own solid-bodied electric guitars.

Appleton carried on inventing and in 1955 produced the APP2 guitar - with an aluminum neck and solid wooden body, this preceeded the Travis-Bean aluminum guitar by 20 years. In 1965 Appleton designed an electric bass with a foot-operated keyboard with hammers which hit individual bass strings. In 1968 Appleton introduced the APP-68 model with a futuristic design like the Heit Swept Wing model.

Source: O.W. Appleton: musician, instructor, designer, inventor (8 December 2017)

Source: The Strat in the Attic 2: More Thrilling Stories of Guitar Archaeology. 2014. Deke Dickerson

Source: The Electric Guitar: A History of an American Icon. 2004. André Millard.