No theoretical reason why r couldn't be done, I think the more common guitar amp tubes are even in commercial production in China (and supposedly they've improv

No theoretical reason why r couldn't be done, I think the more common guitar amp tubes are even in commercial production in China (and supposedly they've improved the robustness too). Bit of a niche market though. glasslinger on YouTube has been experimenting with making some of the more unusual tubes too: https://youtu.be/BXAjspPLzRQ https://youtu.be/BXAjspPLzRQ