https://www.patreon.com/oglaf/posts/ductile-21027549

By request, it's that seething mass of ducks as a tile-able background.

It took me only a couple minutes to find Waldo!

it only took my computer a couple of minutes to load this image!

Forms a Magic Eye image when properly replicated!

Thanks for doing that!

Gridlines are visible though.

The pattern could be improved.

Interestingly, the gridlines occur along the vertical and horizontal centers of the tile pattern, as opposed to along the edge where you would expect them.

It's pretty common to do tiling textures by "offsetting" the edges into the center. Basically what was the edge is now at the center as if the image scrolled itself over. Then you draw out any of the messed up spots so it tiles. Despite best efforts sometimes subtle lines remain. Sometimes it takes multiple attempts to really break it up.

Makes a great magic eye!

OMFG how did you...

Generated a depth map from someone that made a 3d-printable version of it:

https://www.thingiverse.com/thing:3968892

Then used this script, which takes a depth map and tileable image and generates stereograms:

https://gist.github.com/3dsf/efc323b7766171fd2c0331423b8907b9

I think that script could be improved somewhat, the generated image has some weird spots, but it was good enough for a one-off.