rivet counter
n.— «North End Train Center has some intense customers who Colley likes to call “rivet counters.” These are collectors who won’t buy an item unless it is absolutely correct and to perfect scale.» —“Small Business Scene: Miniature railroad store caters to one-track minds” Seattle Post Intelligencer (Washington) Dec. 11, 2008. (source: Double-Tongued Dictionary)
Further reading
When a teenager went a week without talking as part of a school project, he noticed a surprising side effect: Instead of rehearsing a response to what other people were saying to him, he was focused on listening — and feeling smarter as a result...
Aaron in Los Angeles, California, notes while using public transit in Britain he and other passengers were instructed to alight from the front, meaning “exit the car from the front.” Alight comes from an Old English word alihtan, literally, to...