Ray - We both use Stereogram Generator https://indasoftware.com/stereo/

Gene is a Mac Photoshop guy and he also used some 3D modeling and rendering programs. I just use Xara.

We steal shamelessly from one another. I'll post something new on our Facebook page and a few days later Gene will post a new image that incorporates some of the techniques I have come up with. And vice versa.

The stereogram creation process is very similar but we achieve the results in very different ways.