These are a few environment thumbnails I've made using brushes I found online, shapes I made using the lasso tool and a painting them in, and a few new brushes I made myself. I used multiple layers and gaussian blur to try and achieve layering/depth like how microbes look while under a microscope. I also played around with different colours, I feel as though the pale blues and purples work best when I put the bacteria and antibiotic characters on top, I find the more saturated colours make the characters fade while the more unsaturated make them pop. The environment is meant to look slightly more realistic than the characters, again to make them stand out. You can see a few of these thumbnails with characters on top here, where I'm comparing the size between the bacteria and antibiotic.