graphicxtras.com > How to create a square grid filled with colors
A square grid in this tutorial. One made up of multiple square grids. You can make all kinds of random color grids, of course, such as rectangle or
Tutorial by: Andrew Buckle
Works with: Photoshop, Elements
Other tutorials: Tutorial links
Videos: Video tutorials
perhaps thin slivers of fills - the approach is much the same. Likewise, it can be 4 x 4, 200 x 20 or 10 x 30 etc. The basic approach is the same.
Go to the view and new guide layout. Create a basic 4 x 4 with no gutter etc and you will end up with a nice 4 x 4 set of lines which can be filled. Set the view menu "snap" to open and snap to only "guides"
Going to use a square in this example but it could as easily be rectangles. Also, you don't have to fill each and every square. You can also fill the square and then add an additional stamp (image) or another path etc. Select the rectangle tool. Go to the settings along the top option bar and set to square. Set the color for the square and then go to the grid and apply to the guides - the rectangle then snaps to the guide. Repeat this with different colors
You can set the color to any color - best select via the swatches (but it is your choice). If you want the colors to be different in each square of the Photoshop pattern then make certain you set different colors to the one above, left, right etc Also remember to do the same for the cells to the left of the left and to the right of right etc which should avoid matching the left to right and right to the left and top to bottom etc
Go to the edit menu and define pattern command. Add the fill via the edit menu command or the layer menu new fill content or via the layer styles etc
You can re-color the grid in Photoshop by using adjustments such as color filter / hue and saturation etc and the results will still be pattern (sometimes perhaps better than the original). You can also use the Adobe color themes to help set up a nice color scheme for your grid. You can also add additional paths on top of the artwork. You can duplicate the artwork and then scale the grid by 50% and then use blending modes via the layer panel to combine them to create ever more interesting tiles for use in PS. You can also use the results of any of the experiments as a possible brush via the edit menu define brush command (though the result will be grayscale). Or save the result to a PSD file and then use the artwork as a source for displacement maps
I have been mentioning Photoshop patterns but the same artworks can be used in Affinity Designer etc just by saving the item as a PNG and loading that via the various pattern / bitmap features in those apps.