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When I saw that article a few days ago, I wondered whether it might actually be something worthy of the name "sextant". But no, this time that's a stretch too far! No better than a grade school project or a trivial rainy day scouting time-killer. The article itself strikes me as little more than 'clickbait' --cheap filler with an intriguing headline ordered by the published in bulk to sell ads. It also appears to be ripped directly from NASA teaching materials: compare with this document. Please note: I don't object to the folks at popsci borrowing from public domain NASA material. But I certainly object to them doing this without crediting the source. I also object to pseudo-articles --they could have just said "read this NASA pdf". This adds to my feeling that the article was very cheap clickbait (what's clickbait? You'll be outraged when you discover how easy it is to get people to click on just about anything online... really, you will be outraged and disgusted...).

At the risk of repeating myself, I'll ask this broader question: could you build a reasonably accurate sextant at home? Does 3D printing have anything like the required precision at this time? Could we re-purpose some other components to create a really good angle-measuring instrument?

I'm sure some of you have seen a design by Omar Reis that uses a CD case to provide a simple rotating base element. Adding a couple of mirrors and a home-printed scale, you get a nice little sextant with accuracy around a tenth of a degree if you're careful. Primitive but usable and dramatically superior to the simple astrolabe described in the pop. sci. article. Can that CD case design be improved upon?

Could the pivot of a marine sextant be manufactured by any home "shop" techniques, 3D printing or otherwise? How about some digital means of producing scales? Would a vernier sextant be easier to produce than a micrometer sextant?

And what about a more mechanical sextant (similar to some aviation sextants) using a gearbox and showing a "digital" readout for the angle? Could we produce something small and very accurate? Fundamentally, a sextant is a very simple device: it rotates one mirror with respect to another by a pre-determined, readable angle, with high accuracy and repeatability. Surely with some elements of modern computer-driven manufacturing, there's a way to go beyond the traditional marine sextant design... and maybe at a very low price!

Frank Reed