Historically informed ukulele players wanted.
Ukulele: born on 23rd of August 1879 (one of the few instruments to have a precise date of birth). They had nothing else than gut strings, so this is what they used: a first and second string of a guitar.
If you have a uke at home, try it with gut strings, it is so nice, warm and reactive!
If you have an elderly one, maybe more than 50 years old, this try is really worth to, it will start to breath and sing to a new life!
And if you happen to have an old banjo uke, well, it will unveil you a new world, full of rhythm and percussion!
A uke can give you a thousand smiles, give your uke a smile, buy him a set of gut strings! 
