IN-1 Nixies are readily available from multiple sources, but the sockets needed are hard to find and expensive. This design uses 11 Molex 08-50-0106 / 08-50-0108 crimp terminals for making contact with the tube pins.
I printed this with 30% infill and one shell.
Update (21. apr. 2013): Added a second version with improved snap-fit for molex terminals.