No such thing as perfection
What is perfect to you might not be to the next guy

Examples.
I prefer one big belly hook over two smaller ones - I know lots of guys who like two smaller ones. Which plug is perfect? Depends on your preference.

I don't like sealed hanger plugs, I like swivels (IMHO, hangers give too much leverage to the fish). However there are LOTS of guys who like hangers.
I've done the same plug both ways to satisfy different guys but again- Which one is perfect?

No such thing as perfect

As for setting a design, in my experience it generally takes at least a half dozen generations/variations before I'll build the jigs to copy it exactly.