File :-(, x)
Okay. I have illustrated mine, because I can't explain it in word.
Basically the box is too high to allow you to sit down or crouch, too short to let you stand comfortably. You'll wake up with a scapel glued to your hand. A tape will play as you wake up, explaining that there is a way out. There's a remote contol, one that will make the box collapse harmlessly, and the locked door open. This remote is in inside your stomach. The scalpel will help you get there. If you cannot, then you'll stay in the box.
The lights will go off. You'll be left in total darkness, total silence. I'd watch with an infrared camera, enjoy the show.
You won't be able to sleep, because you can't sit, crouch, stand, anything. You'll slowly, slowly die, legs aching.
Not much gore if they choose to slowly perish, but them trying to cut themselves open in the dark, unable to see anything, now THAT would be fun.