Best way to make lights behind glass?

[MuscleCarFreak]

I wonder what technique you use to make the lights on a modern car, which are most of the time glass that's aligned to the body shape and the actual lights/lamps behind it in a chromy molding.

I'm modelling a design of my own and as of now, I didn't leave spare place for the lights, I just did a "closed" body.
So now I wonder if I should cut out the light outline and then negatively extrude the edges or if it's better to make a "real" hole with boolean and then close it again afterwards. Or is there a boolean operation that does this at once?

[Flexdude]

the way I do it is

create the car as a shell.
cut the shape of the light out into the body shell using the line cut tool.
detach the light from main shell.
use loop select to select the edge of the light.
hold shift and drag inwards to extrude light (by a small amount).
select front of light faces and hold down shift and drag so level with previous extrude.
weld the points of this face to the points of the extrude to create a panel (as I would call it).
this create like a light cover.

Next:

again select the front faces of the light and shift drag backwards into the light to copy the faces.
then select the inset tool and inset these faces.
select the new inset faces if not already and move them back wards into the car to create the depth of your light.

Then create any of the bits inside the light.
This is the way I go about it mainly (not necessarily the best but it works)

If you have no idea what im going on about I'll do some pictures for you later

[MuscleCarFreak]

That sounds good, I think I get what you mean, thanks! I'll try it later and report whether I was successful.
I tried something similar myself before, but always got smoothing or normal errors, probably because I forgot the detach step .