Just about every major guitar maker has produced a ukulele (often misspelled ukelele) at one time or another. Martin offered three ukulele models to its customers in 1918. The diminutive 12- and 17-fret instruments were followed in the 1920s by concert and tenor models, while the Martin 5-K from 1922, with its koa wood body and abalone inlay, is much in demand among collectors. Gibson introduced its first ukulele in 1926. The highly...