How would I go about replicating the following pattern in Photoshop, with a different background color than this gray one?
Of course, it would be best if the pattern could be on its separate layer, so it can be compatible with any background color.
I’ve tried using the pen/pencil tools to draw some lines and then blurring them and reducing the opacity, but it never looks quite like this.
How can I reproduce this pattern with a background colour of my choice?
I guess this one is made by filters I am not sure but you can get similar effect using water paper filter
filter > sketch > water paper
just create your background of any color and then apply this filter.
you can maximize the values(highlighted in red) as well to get your desired output.
hope this will help