Uh, either my eyes are in the wrong sockets, or these images are reversed. If you cross your eyes hard enough so these images match up, they should be 3d. I flipped them around in an image editor and it worked. Pretty cool, really.
I’m not sure what the exact term is, but I usually call these “reverse” stereograms. They look inverted using the normal method, but if you cross your eyes the other way, it pops ‘out’ instead of in. And I don’t just mean that it fixes the view, normal stereograms go into the page/screen and then pop up... but these float above/out-of the page/screen. They are also harder to do sometimes...