I tried to create optical illusions without success before. "Black and white" seemed like a good excuse to retry it with all my learnings. I'm pretty happy with this one.
The trick is to use alternating prompt to create a base image and then iterate img2img alternating between the "vase" and the "silhouette" prompt. Also, I think the Euler A sampler is too unstable for this; DDIM seemed to work better.
