Photoshop Idea - Pattern Preview in Half Drop Repeat.

I was thinking of more complicated patterns for wallpaper or fabric… Maybe there is a way to do it, but I haven’t figured it out yet...

You should also check out the Edit > Fill > Script options.  There is a near infinite ways to display patterns with that.

Do you know you can do it manually?

After turning on the grid I dragged the zero, zero point to the centre of the top left circle. That made it easier to move copied layers to their precise positions, but they snapped to the grid so super easy.

Drag a square selection (which snaps to the grid) and define the pattern.

You can use the pattern in several ways, but I like to do it as a layer style as it’s non-destructive and easier to scale.