This is a 1:1 scale model of the top of a 12AV7 radio tube. Its solid, meant to be printed with 0% infill and no bottom layer, which will make it hollow so you can print it with clear plastic and used as a top for a DIY LED 'nixie' display. see my comment in HaD article
print with 0% infill, no bottom layers, I used 2 top layers. it will create a hollow radio tube shell.
This is the best print I could do.