File / new document for the line brush. Say 2000 x 2000 - you can always scale the document later. Select the rectangle tool, set the color to black via the toolbox and set as shape layer via the top options.
Draw the rectangle from the top of the document to the bottom and create a thin rectangle - add this to the far left and then add another a few pixels away (leaving some white gap) perhaps with the same size of rectangle or slightly different. Repeat this over and over for about 1/4 of the document though you can do this all the way across the document - it is just quicker to just use 100 or so and repeat them.
They can work on a gray scale model so you don't need to have just black as the color for your artwork, you can use gray scale as well. They can be thin or thick across but you can also vary the color. Unfortunately, the color of the custom shapes / rectangle has no random variability such as color dynamics. Easiest way to add the art and change the colors, is to have the swatches panel open and select the gray scale colors so you can quickly click the colors and then apply the shape that way.
Select rectangle layers via the layers panel and layer menu and combine shapes and then unite shapes. With that set selected, Alt / option key and duplicate the combined shapes. Move duplicated layer away from existing set.
You can create multiples with different widths. You can then combine them all into a single shape layer by going to the layer menu and combine shapes command and unite though if you use the unite, the color for all those lines will become the same (you may prefer instead to use the layer menu and smart objects and convert to a smart object and that keeps all the different colors). Once united, you can then duplicate that set multiple times as well as change the color of the united set and fill the entire document or just create multiple copies
Select a layer and then check the show transform controls is ON (top corner of the control bar) and use the bounding box / transform controls to now stretch the designs to the right or left (making the them bigger or smaller than before)
This can be repeated with all the layers or just one. Another option is to drag the layers on top of the others as well as transforming the layers. You can also simply re-select all the layers and then go to the layer menu and smart objects and convert to smart object and move that smart object and duplicate etc
Select the rectangle tool. Apply the rectangle in different locations and width. You can add all kinds of additional rectangles to the artwork to add some variation and randomness to the preset. You can also change the opacity and the blending mode of the rectangles added to the work to create even more unusual combinations and creative possibilities.
Or more combinations and using blending modes (such as difference) to create an even more intense designs. You can repeat this over and over and applying them with the difference or exclusion or darken can create some weird combinations of artwork that all can be stored away using the define command found in the edit menu.
You can also create a design that is horizontal. Simply create the rectangles horizontally or just rotate your vertical design. As with the vertical, the same can be done with the horizontal.
The artwork (if shapes) can be modified further by using layer menu and layer styles and perhaps add a shadow or perhaps add a gradient overlay.
Flatten the layers and edit menu and define command. You can then go to the brushes settings found in the window menu and add a number of additional settings to the stroke such as color dynamics etc and then define that as a new preset.
For example, select the paint tool and set color to black and apply newly define stroke. Set color to red and apply it and then set the color to blue. Go to the panel and tip setting and squeeze the size vertically and apply it again. There are 1000s of other ways of using this preset, you can also use it with the other tools such as blur, smudge, clone, art history etc to great effect
You don't have to just use them as as strokes, they can be used also as a seamless design as well via the edit menu and define pattern and then use with fill layers etc and they can also be combined in multiple ways to create even more designs