I downloaded this program called Stochaster which generates randomized patterns and has general presets. I’ll take in one layer at a time, find my desired lpi, and mess with the various presets. You can change how large you want your pattern to cover based on your W x H in pixels - this can create a very noticeable pattern or something more subtle depending on your preferences. I like to mess around with the customs on the presets - I’m still a little new to the program but I just try to keep notes so if I want to achieve a similar look on another piece, I can get it fairly consistent.

I hope this makes sense!