[cjbillington]

The lasers alone set you back many tens of k so it's not really possible to do on the cheap presently, even if a lot of the cost is expertise and the high overhead of R&D costs when only producing small number of units.

Oh and to know if it's any good you have to either build two (ideally more) of them to compare against each other (ideally using different approaches so their errors are less correlated), or have access to a clock better than the one you're building to compare to. So you can rarely get away with building just one if you want to know if you've succeeded.

Source: I work on the software for these portable optical clocks: https://phys.org/news/2025-07-quantum-clocks-accuracy-curren...