There's also a fantastic Youtube video in a neutron beam facility of a Moka pot, in which you can see the full process of brewing. The water and plastic handle appear 'black' as hydrogen scatters neutrons so strongly.
Wow, it's really a shame about the new Bialetti pots. I've recently gotten one off Amazon and now I'm not sure if I should instead hunt for a used old model.
I really like that video. However, I think this could have been done with X-rays by adding heavy salts (ex. sodium metatungstate or vastly more hazardous thallium salts) to the water or using a heavy organic liquid (ex. diiodomethane).
However, if you have a neutron imaging beamline you probably are motivated to make a cool demo.
https://www.youtube.com/watch?v=VESMU7JfVHU