Summary

Hi, I needed a low cost small lamp cap which I could also change the light color from.
I used buck cheap G9 12v lights from Action, bend the pins straight and connect a luster terminal to it.
Beware of heat that could occur when the light stays lit. I use them for strobe lights so that was'n't a problem for me.
I added a cap with ventilation holes and the base has two standard ventilation holes, should be plenty cooling to avoid problems.

Printing the cap: use same color plastic as base till 10mm height and then switch to transparant filament.
The diffuser isn't needed unless you want to get another color of light, best to use transparant color filament for that too.