So I was thinking about how Deckingman used a threaded mounting plate so that he could get the complete threads for the heatbreaks, and also wondering if costs could go down by splitting the complexity of a single part into multiple parts that, combined, cost less.

I then had the above idea, where there's a small coaxial-ization section and a metal sock that goes over it, where it's fixed in place by grub screws that both hold the sock in place and seal the internal channels.

I still feel like it'll probably cost more than just 1 single part though.