I like these:
https://www.amazon.com/Levys-Leathers-M19PR-BRG-Mandolin-Burgundy/dp/B000XPPPXO/ref=sr_1_4?ie=UTF8&qid=1485804190&sr=8-4&keywords=levy+mandolin+strap
I like these:
https://www.amazon.com/Levys-Leathers-M19PR-BRG-Mandolin-Burgundy/dp/B000XPPPXO/ref=sr_1_4?ie=UTF8&qid=1485804190&sr=8-4&keywords=levy+mandolin+strap
Randy Hogan made a nice braided leather strap for my Collings MT A model.
https://www.facebook.com/HoganMandoStraps/
Also, Pinegrove Leather in England made me a nice 1/2" wide flat leather...