Self crucifixion is possible, as Deiselad says. Me too started in my teenager years with very simple constructions.
Today I have my own cross in a little "secret chamber". It is mounted to the wall very hard, so it cannot fall down while I´m hanging on it. For self-crucifixion I´m wearing special leather "Cuffs" - very soft ones. On there backside they have stability little rings of steel. I put an stool in front of the footrest. This footrest goes down in an angle that allows my naked feet nearly no hold but a little. Where my wrists and feet will take place are strong hooks on the crossbar and over the footrest. The hooks show about ten centimeters high to the roof. That means when I´am hanging on those I can fight and struggle as much as I want. The holding rings of my leather "cuffs" at my wrists an feet angles cannot loose hold.
So I stand on the stool, get on my toes and stretch myself high until I get the rings of my wrist-bondages over the hooks. Then I can let my sink down a little bit and make the rings behind my left foot on the hook behind the footrest, then the right one. The hook behind the footrest is longer than the ones for my wrists. When my feet are fixed side by side on the foot-hook, I´am really crucified. I can feel all Feeling sensations on the cross: being naked and "helpless" and feel the ache starting, what makes me start to "dance" on the cross. Sometimes I can stand a completely hour or longer in this self-crucifixion. But I can leave the cross when it is getting too hard for me.
