Sockets for sub-mini tubes. I finded them.
https://www.mouser.com/Mill-Max/Connectors/IC-Component-Sockets/_/N-211lk?P=1z0zl2rZ1z0x9blZ1yvgcdj
Not cheap, but certainly a good idea.
I expected "not cheap" to mean much more $$$ than that. Seems pretty reasonable. Wish I had one for my Uber Tuber build. Nice find!
Boom, I feel like I need to build an Uber tuber now.
Pretty sure those sockets are for metal can transistor types. Would be a tight fit to use for sub-mini tubes :-\
Maybe the TO-99 sockets will work too?
http://talonelectronics.com/shop/item.aspx?itemid=7003
And then there is this...
http://mhdtlab.com/socket.htm