Look at what Elderly Instruments has for sale:

Dopyera Bros. 12 instrument collection plus historic workbenches. Check out that resonator fiddle!

From Elderly:

The John and Rudy Dopyera Collection

We are very proud to offer for sale the combined collection of John and Rudy Dopyera. Few instrument makers represent the American Dream quite as completely as these two inventors, innovators, marketers, and all-around creative force behind both the National and Dobro companies.

The Dopyera brothers were born in what is now Slovakia, and came to the U.S. with the wave of Eastern European immigrants around the beginning of the 20th century. (In fact, the word "Dobro" is both a contraction of "DOpyera BROthers" and the word for "good" in their native tongue.) Engineers, tinkerers, businessmen, and accomplished musicians (their family had a history of violin making going back centuries, and Rudy was by many accounts an exceptionally talented and soulful Gypsy-style violinist), the two Dopyera brothers combined their Old World skills and traditions with the booming technology and futuristic tastes in art of pre-WWII America. Who else thought that spun aluminum might be a good material for sound projection? Who else engraved beautiful Art Deco designs on the bodies of their guitars? Only the Dopyeras.

The unusual, experimental, and mostly one-of-a-kind instruments in this collection – John's unusual (and spectacular sounding!) resophonic violin, Rudy's balalaika-inspired Lullabyka, the Art Deco-influenced steel body uke and tenor guitar, even the actual workbench on which John perfected the fabled tri-cone resonator system – are uniquely American (and uniquely Dopyera) innovations.

There's no doubt that many of the great blues and slide guitar players owe their careers to these radical innovations of the Dopyeras; and there's no question that both country and bluegrass music developed a whole new voice after the introduction of the Dobro. Because of the Dopyera brothers, American instruments – and American music – have never been the same.