These pictures were generated by Bing's image creator for the cover art for my forthcoming book "Secrets of Liquid Filling" Prompt was some variation around "Picture of a bottle filling machine for a book cover"

Either 2 or 4 will be the final cover. I like 4 slightly better but wonder if flying bottles are the best image for a book about how to keep the bottles from flying. 1 or 3 would be fine also but a bit less fine. 

If you have any thoughts, let me know in the comments.