graphicxtras.com > Turn custom shapes into patterns in Photoshop - create seamless tiles using vectors tutorial
Patterns can come from anywhere. You can use part of an artwork, part of an image, an image, multiple artworks, effects etc and much more. The key thing with all the patterns is that you have to create / define the tile via the define command. If you want to create a seamless tile then just don't add the artwork at the edge of any document or selected region.
You can combine multiple artworks based patterns by using blending modes such as darken. If the tile is applied as a fill new layer (via the layer menu) then you can quickly either create a new layer (use the same or other artwork) or use the duplicate layer command. Some blending modes work better than others and depend on the actual content / color of the artwork. The example below shows the same tile as above but duplicated and then applied using a darken blend mode (via the layer panel) and then shifted to fill the gaps (this can be done using the move tool in Adobe ® Photoshop ®). The key thing here is the tile has enough space around the central artwork to avoid any overlapping of the layers. You can repeat this multiple times though the actual results depend on the source material, sometimes the result of combinations will be just a mess
If you use the source material vector as a layer then you can use all number of combinations. The key thing here is that using the artwork as a layer is that you can remove the background and use transparency to combine the artworks. You can also add transformations into the definition of the tiles such as adding a tile with the source vector and then the vector upside down or the vector rotated 90 degrees or 45 degrees or any angle. You can also scale and shear the vector artwork or perhaps make multiple combinations of different groups for the tile. You can then combine them all using the new fill layers content. If you are using a tool such as Affinity Photo then you can rotate the fill layers (as well as scale them) but sadly you can only scale them in PS so any transformations have to pre-generated.
You don't have to use the same color, you can use them in red and green or perhaps filled with effects or perhaps with gradients or with tiles themselves and they can be then re-shuffled in a huge number of ways. You don't have to always keep everything neat and tidy, the artworks do not have to shift them equally apart. Set the color of the vector layer via the fill setting or perhaps give a stroke setting as well or a different color stroke setting or just set only that. You can then combine the tiles again in numerous ways by creating multiple layers and adding them with the transparency (just remove the background - if locked, unlock the layer by clicking that little padlock)
You don't have to use a fill, you can just use the stroke with the vector layer and that can be set via the options along the top of PS. You can then create all kinds of interesting sketchy / rough looking artworks. You can also create perhaps those layers over an existing background image such as a gradient or photo. Sadly, PS does not have the width profile / beautiful strokes feature of Illustrator so all the strokes are the same sizes all around such as 3px or 5px only. You can combine them using transparency as well as blending modes as well as use different sizes of tiles as well as different opacities and different colors of stroke
The shape doesn't need to avoid the edges / seams of a tile. You can add the vector layers or pixel fills over the edge or you can just use a selection but a selection that does not enclose all of the artwork. The result will be a tile that has an edge
The beauty of the vector artwork is that it can be used to any size so you can create all kinds of artworks that look like a pattern but definitely are not created via the usual define command or the random fill / scripts feature etc but are just created using multiple applications of the vector artwork in different colors and sizes and angles. You can also use the filter menu offset command to create far more interesting combinations of designs