Twister
Your assistant enters a bizarre contraption which consists of an elevated larger cabinet with a smaller cabinet sitting on top. Her legs remain visible through the bottom of the cabinet, and her face is visible through the open frame section at top. A crank handle is turned, locking the head in place. The magician then turns the assistant's head through 360 degrees again and again, twisting it impossibly on her neck. Her face and neck seem unharmed, but what effect could this possibly be having on her body?
The lower cabinet door is now opened to show that the assistant's body has been twisted into a spaghetti-like mess! After the audience has been given time to appreciate the effect, the cabinet doors are closed, the assistant's head is spun again, this time in the opposite direction, and the crank released. The assistant emerges unharmed from the cabinet (hopefully to thunderous applause!).
Our model of this great illusion is the ultimate in practicality. The prop is durable, built to last like all our illusions. Assembly takes less than three minutes, making this one the prop you'll use again and again under all conditions.