Please don't give interviewers any ideas.

Most obvious options:

- Use a large bottle

- Use a small lightbulb

- Construct the bottle around the lightbulb

- Construct the lightbulb inside the bottle

- Cut off and replace part of the bottle; this can be done almost seamlessly

- There's no technical reason that a lightbulb needs to be made of glass, so we can make a collapsing one, and unfold it inside like a ship-in-a-bottle

Just grind it into a fine powder and pour into the bottle.

Done.

You. I like you. You're like an evolutionary algorithm satisfying a fitness function. Spirit of the problem completely ignored, but problem bloody well solved.

(S)He's really more of a wave function

I couldn't find a picture (link?), but I would just blow he bulb inside the bottle. Alternatively, use the bottle as the bulb, add filament, pump out the air, and put on the cork, but I'm not sure whether that qualifies as a lightbulb in a bottle.

Depending on the wording I would assume that the small lights in a fridge or a small flashlight or maybe even Christmas lights count. I think those should fit through many bottles pretty easy.

or a big, wide opened bottle

At what point does a bottle become a jar?

about the same time a flask becomes a beaker. As Bill Nye has taught a couple generations of kids, you know the flasK has a necK. :-)

With a pencil and a couple of rubber bands.