12AV7 top
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
http://hackaday.com/2015/03/03/nixie-inspired-7-segment-display/