Check out this great DIY 3D Stereogram project, brought to you by Richard Clarkson, one of Becky’s students at SVA’s Products of Design program!
A Stereogram is an image that can be perceived with depth perception via one of several viewing techniques. This is the basis of 3D imaging and is in essence assisting one eye to see one image and the other to see a slightly different image. The above gif is a wiggle Stereogram which can simulate the effect but is done with a different technique see here.
Naked-eye Stereogram viewing can be a lot of fun and is made much easier to learn with this viewing assistant. After a bit of practice you might be able to view the 3D image without the viewer at all by using the same cross-eyed to uncross-eyed technique explained in this tutorial.