I call this "reading" even though there's very little text. The stereoscopic drawings, inspired by the editor's favorite childhood math book, are among the most engaging 3D pictures I've ever encountered. A lot of the drawings are purely abstract, while others show a narrative; my favorite of the latter shows the route of a snail around all the surfaces of a house, without showing the house itself.

The book has built-in lenses in the cover, which I don't use because I can freeview.

It took me years of searching various used book sites to get a copy of this, and it was absolutely worth the wait. It's an optical delight that tickles my brain.