Magic Portal Illusion Version 4: a favorite illusion- with three separately moving colorful strands that seem to pass in and out of a 4th dimension. The mechanical principle employed is similar to that of a lead screw and slider type actuator, except here translating the slider up and down rotates the helical strands at just the right rate to produce the illusion. An amazing 3D print creation by Ada Cohen from 2019. ➡️ Follow the link in my profile for info about where to get this Portal Desk To