Foden: In 1912 to 1917, Martin made guitars for concert guitarist William Foden. These are similar to the standard Martin models, but have simple soundhole rings and a 20 fret fingerboard (instead of 19). Made in sizes 0 and 00, the styles were similar to Martin's Style 18, 21, 28, and a pearl trim model. Only 27 of these guitars have been documented to date.