I've been reading your suggestions on self bondage and I'd like to contribute one more:

DICK TIMING: This is an alternative to the key in the ice block: To use your own dick as the timer. I've tried it only once and I've managed to get free without waiting to see whether it would work, so I don't know what would have happened.

First of all, I left the keys out of reach from where I'd be, sat on a chair and bound my ankles together. Then I tied a strip of cloth (made from a torn bed sheet) to the left hind leg of the chair. Before tying the 2nd end of it to the right hind leg, I wound two loops around my hard cock, so I was bound to the chair by my own erection (I had previously dressed my precious tool with two thick socks). Finally I cuffed my wrists behind my back. As I saw it, I could only get away from the chair and crawl to where the key was after freeing my dick, and that could only be done when the erection was gone.

The problem was, the more I tried not to think about it, the more excited I got and the harder was my dick. I eventualy managed to move the chair toward a low table and, rubbing against the edge, managed to undo the loops. I'm not sure there's a way to get free. Maybe, if I fall asleep...Then again, if I wake up and the loops are still in place, I'll have to move fast, otherwise the "timer" will be reset for another session.