Thanks for the detailed response! I think this is helpful, where it seems to run into trouble is the dithering patterns retaining their white portion. Is there any way to kind of... "collapse" patterns into a single layer so it treats them like it does images? If not, I think this may still be useful to get what I'm thinking, just with a more image-based process instead of relying on the drawing tools. (This may end up looking better, anyway.)