For people fond of custom ringtones, Ringtone Maker app makes it possible for you to make/save ringtones from your favorite tracks. The app which is still in beta works on both on Windows 10 and Windows 10 phone.
The app is rather basic but functional, just open a track, pick your favorite part from the track by sliding, and then save it to your phone. It also gives you the option to set it as the ringtone, then and there.
Find the app in the store here