Sirds 2.4 for Mac could be downloaded from the developer's website when we last checked. We cannot confirm if there is a free download of this app available. This Mac app is an intellectual property of Katsura Shareware. The most popular version of the program is 2.1. Sirds for Mac relates to Design & Photo Tools.
From the developer:
Sirds lets you create Single Image Random Dot Stereogram (SIRDS) or Single Image Stereogram (SIS) from depth map images and pattern images.
SIRDS or SIS is an image giving a three-dimensional representation of a solid object or surface, and it does not require any equipment such as red & blue or polarized 3D glasses to view the stereo scene. You just need to learn how to view it in certain way with your own eyes.
You may want to check out more software for Mac, such as Absird, which might be similar to Sirds.