Here in Franklin county (specifically Washington and New Haven, Missouri) the zither reigned supreme for more than a century. There was a zither maker of some note in Washington (sorry, I haven't any idea as to his name) There are numerous concert zithers in various personal and public collections, locally. In my town, New Haven, we had a gentleman who was well known and beloved for his zither playing. Erwinn Otto Mann was a local educator (teacher, school superintendant) who delighted thousands with his playing. He also repaired and restored zithers (and autoharps and hammered dulcimers and other stringed instruments) in his shop which he called "Shady Nook". He was a delight to spend time with, insterspersing his stories of the early years of education in our area (his first classes were taught in German and English), with bouts of intense zither plucking.
E.O. Mann died a couple of years ago, he was 91. His daughter Carol plays his zithers now and showed me something really interesting that her father had devised (I don't know if it was his invention or not) and that was a zither shaped poster board insert which was placed under the strings and had the pattern of plucking indicated on it which would allow the player to follow precisely what strings to pluck and when in order to play a reasonable rendition of the tune. She had dozens of these pieces of poster board with all the traditional Christmas and other "churchly" music we use in Franklin county services on them (lots of German Evangelical Reform tradition here, now either Lutheran or United Church of Christ). She said her dad developed these inserts to help his students learn to play the zither. I suspect he followed an existing practice and adapted it to the music of our region.
I prefer the auto harp (also known as the "idiot zither") but since zithers are still found in local resale and antique shops here I might try my hand at playing one using the posterboard insert method.