Radio is a bit (just a little bit) of an interest of mine having worked for a radio retransmission station for many years and being a licensed (albeit not very active) radio amateur. Radio hams in general are enormous Makers, although I regrettably never have been.
This article (at boingboing) on handmade vacuum tubes equals my recent post on the Memex tide calculator. Awesome!
See also Aleksander Zawada's page on making vacuum tubes.