How do I make a *.sbsar file with "input images" function with Substance Designer?

Hello,

This is achieved using Input nodes.

If you wish to create content and filters for Painter specifically, the Input nodes should be configured according to their purpose in Painter. The 'Creating custom effects' section of Painter's documentation provides guidance on this topic.

You can also use the Substance graph templates dedicated to Painter for getting started. These are available in the  'New Substance graph' dialog.

Feel free to get back to me if you require further guidance.

Best regards.