A Tap Against the Plastic

My fingers twitched, and suddenly the stiffness completely vanished from my joints! I stood inside a snug plastic tray surrounded by cardboard walls. Curious about what was beyond, I took half a step forward and lightly tapped my knuckles against the clear plastic window right in front of my face. It made a crisp click and bowed outward slightly under my touch. My limbs actually move, and there is a whole wide world right on the other side of this clear barrier!