my aim is to self fist and would love to self fist with others.
I was told that you need to be able to stretch your hole a fair bit wider than a fist as when you self fist, the angle you drive it in at is wider than when a fister slides. So are your toys wide enough? My toys have got bigger over time and are the width of a can (circumference 8.25 inches = 21cm), while the average man's hand is 8.6 inches (= 21.85cm).
then there's the flexibility. for me, on my side lying down, with one leg straight and the other bent is the best but it's that damn thumb knuckle that stops it! Another good way is standing with one foot on a chair, back arched, arm against a wall and reversing onto your fist.
When I'm in the mood to stretch I watch this stud, he makes it look so easy.
[think before following links] https://xhamster.com/videos/tutorial-and-tips-to-start-fisting-and-deep-streching-to-do-with-yourself-or-others-xhRfb2u
Hope you manage it. Hope to hear any success stories on here.