I set a personal record of being handcuffed for 3:35 this week. The release was the key was in the middle of about 2.5 inches of ice in a McAlister's tea glass. After putting the key in, the rest of the glass was filled with pre-chilled water and a shaped wire from which it was to be hung. The spare key was on the other end of the back yard.
It took about three hours before I could even see the key in the ice, hanging from about 12 feet in an over garage storage area. I let the melt fall into another plastic glass. The ice came loose from the wire and appeared to be a cylinder. I had thought ice melts evenly but apprantly air that comes in contact with the top of the ice cools and starts to sink, preventing ice further down from melting as fast.
For shorter durations a "salad fixins" cup from Newks, the BBQ sauce cup from Dickies, or prepackaged fruit slices from the grocery store should do. The smaller cups with sloping sides should survive being frozen several times.
I also tied myself to the bed in this position (no tickling, though) using cuffs, a chain, and a combination lock. Since I had started around 4:35am, I used a timer to turn on a light after about 30-40 minutes... or so I thought. Time seemed to drag more slowly than when I did a spread eagle self-bondage on a bed I had years earlier. My watch beeped at the top of the hour (5am) and later panic would set in as I realized the light wasn't going to come on. After what seemed to be a really long time my watch beeped again at six and after about ten more minutes or so, the light finally came on, I had forgotten the "time now" needed to be advanced more than it showed on that particular timer.
Also hog chained myself a few times this past week and had a backup key delivery system. If you have a windup alarm clock, split one end of a packing peanut and flatten the other end. Once it is working and the alarm time is set (make sure the wind up handle is horizontal), put it on a shelf or piece of furniture and balance a backup key on it. Let it fall into something where the key can be found and it won't bounce.