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stil reading the forum and parent site,
something came across my mind
does it exists or someone has a (glass covered) peakhole

i'm thinking of making something like a porthole into me kettle.
take some 28mm pipe make a flange, put some cork between
glass and flange and use a "springclip" to secure the glass.
solder it to the top of the boiler and voila?

any suggestions are apreciated
or does it sound stupid to you folks?

let me know what you think of it, good or bad.