Origami is a free toolkit created by the Facebook Design team for Quartz Composer, the visual programming tool that's available with the Apple XCode development environment. Origami provides patches that can be added to your Quartz Composer library, to create interactive prototypes without programming. Quartz composer's UI allows you connect patches with wires (or tubes, if you're familiar with that metaphor) to perform tasks or set behaviors and properties.
Jay Thrash's video explains how to use it. Jump to 8'22" to see the demo.