I was fortunate in having a friend who was a professional Blue-grass
fiddler who donated his used strings for my Violanos. They were fine
quality fiddle strings available at any of several nearby good music
supply stores. There is really nothing special about them except that
they were not the "el cheep-o" ones.
Probably more important to the tone is the type of rosin used in the
Violano. For many years I made and sold rosin blocks and found that
there is a significant difference in the sound obtained from various
types of rosin.
I did know a Mr. Don Reck in western Michigan about thirty years ago
who told me that he used all gut strings on his Violano. I never heard
it so don't know how it sounded from personal experience. But that's a
distinct possibility, I suppose. I never used any except standard good
quality violin strings on any of my Violanos.