There's this weird moment in refactoring code, when after hours/days of redesign, changes, and testing you bask in the glow of a job well done and all the improvements you've made... before running the code and seeing absolutely nothing different in how it functions from the outside because that's what refactoring means.
I suspect that people making physical components with care and precision that they know will never be seen, and will be noticed only in the absence of problems coming from them, most have a similar experience. You feel pride in the job well done, but it is also somewhat anti-climatic when you look at the finished product.
