I have a few B7 valves and quite a few B5 and B4 valves but did not have a suitable socket to include in my homebuilt valve tester, I was able to make a B5 socket from a piece of black insulating material (some sort of phenolic) I found in my parts bin, B5/B4 valves have a spring contact built into the valve pin so I thought a plain metal tube is ok to use for the socket contact - I used 1/4" brass rod turned and drilled in the lathe, the same socket doubles also as the B4 socket. See original post here
https://www.vintage-radio.net/forum/...d.php?t=166943 the homemade B5 socket can be seen in the video at the back/right.
Wanting to try out my recent 3D printer purchase, I drew up a B7 socket base in Fusion360 and after following some youtube instructions a B7 base almost magically appeared on the printer bed. I've run out of 1/4" brass rod and will pick some up this week to finish it off.