Tried this metabolism drawing with Visio. I also subscribed to EDRAW but could not figure out a better way to do it with that software. Key problem here is the enzyme labels on the circle. The circle is easy enough but if you want to segment it - that is a problem. When it is not segmented you can move it to the back but that means the product boxes in this case need to be non-transparent or the line will show. Overall I don't think it looks too bad - just a question of what kind of...
