Be careful how you ask someone to copy a collar. It is possible to get nearly all of the dimensions right and still not get the "look" you want, or the feel. I gave one of my best shirts to Ascot Chang once to copy, and when they produced their best shot at it, it looked totally different and didn't really fit. Different lining, slightly different placement of collar stays, etc., all adds up to a different experience. Same with Chipp. They will send your shirt to a factory and have your own personal pattern made (they don't really do their own bespoke). But the resulting product will not be the same. So do bring in the shirt you like and try it on, have it photographed, or whatever. And then be prepared to have their effort be a little different the first time round.