Thank you for the welcoming and the suggestions, guys! I just downloaded the "MadJik All plugin pack" and I find quite interesting effects there that I will experiment with.
Back on the topic. I regularly use multiple layers of the same modified object (a 3d model made in Rhinoceros) that then I stack vertically or horizontally for a comparison purposes to show my clients what's the difference. It would be nice if the functionality I was looking for was possible with making a plug-in. Out of curiosity, is it possible to at least have a "multiply by" option in the Canvas size window, so that the image could be easily doubled, tripled vertically or horizontally? Basically it could be done with typing 200% or any other % in the "By percentage" box either for the vertical or horizontal direction, while the opposite direction is locked/inactive. I think that the easiest way to implement this is to add small checkboxes (aka tickbocxes) right after the "Width" and "Height" settings. And by default they are both selected. Is that possible? Currently, I have to use Windows' Calculator to figure out the necessary image resolution multiplied by the number of layers that I want to stack in the final image.
PS: These are examples of how I stack layers to make comparison images: