The main reason spinning a can works is because it induces convection inside and outside of the can, which contributes to more collisions and better distributions of collisions. If the warmest soda is in the middle of the can, the cold molecules near the can walls will reach a temperature similar to the ice bath and thud the rate at which heat is transferred becomes stunted.
For lettuce, you’d have better luck finding a way to pass cold water between the leaves, much like having fins on a heatsink (surface area).
No, a lettuce spinner is a little basket inside of a container with a handle that you can spin to turn the basket. You wash your lettuce and put it into the basket and turn the handle. The centrifugal force (I think) causes the water clinging to the outside of the lettuce to drain into the container.
I think if you filled the container and basket partially up with ice or crushed ice) and some water, it’d achieve the same result as the machine someone linked above
