after print the bulb, you need to cut the bulb bottom parts ;-)
need 2 screw and bolt M4 x15mm for assembly the lamp holder and the extension.
tip: insert the electric wire before gluing the two parts
Technical
I printed the bulb by PETG (HDglass) and spiralize function set on my slicer. The base and the extension was printed by PLA, separated and then glued toghether.