This is not a super O method necessarily but definitely have had success with hands free.
I use a foam yoga mat rolled up, straddle it while sitting on top and rock back and forth. You have total control over pressure and sensitivity.
The other method is to take the yoga matt and place it vertically on a corner of a wall, at the base where it meets the floor.
So, a hallway where two walls meet would work. This gives your legs room on the right side and left side when you get on your knees. You are in doggystyle position, the mat acts like a nice cushion for you to bounce on and get railed from behind.
This works for hands free, but is intense. Within minutes I have shot ropes all over the place from a rough session. Place a towel down and don’t be afraid to shoot it out because the bouncing is what triggers it for me.
I am very close to squirting whenever I do this too so be prepared for a mess.