I learned to tie a fiador knot from this video https://youtu.be/mMcX3ZQM9n4. After tying many rope halters I am now learning to repair and make leather halters.She also has good videos for making the eye splice and butt splice for lead ropes.
I just purchased an old Osborne rein rounder from Bruce Johnson Leather Tools https://brucejohnsonleather.com/. They're hard to find (and expensive) but I am pleased with the job it does.