Velvet-hand illusion
A hand-made device to demonstrate the velvet hand illusion, i.e., a tactile illusion that generates a soft, velvety feeling on the hands when they are lightly pressed together and moved slowly across the wires (see video below).
This model includes a passive and active touch mode, as well as varyingly-spaced wires to allow people with different hand sizes to effectively experience the illusion.
Theory
The contralateral surface of the hand gives no friction so the brain of the participant infers that the hands are moving on the surface of some objects. But the contralateral surface of the other hand gives no friction. Therefore, the brain concludes that the contralateral surface of the hand is very smooth and soft.
Since VHI requires both compressive stress and tangential stimulus, it is caused by not just one of the four varieties of mechanoreceptive units, but two or more of them.