Featherweight Wheels inserts

[robotic_ants]

If you search for terms such as "connector", "joiner", "coupler" or "threaded" as well as what you've searched before (3/8, 3/8 BSP or M10) you might get better results, generally the listings don't use the word "nut". You mostly find them used as brake pipe connectors.

I've made wheels using a similar method but just using normal steel ones as they seem to be more widely available than brass ones.