I recall sometime this year seeing a show where they took the front door off, cut out a hole and installed a window in the door.

What I'd like to do is install a half-lite window with some sort of design on it,
or perhaps a smaller 3/4 size archtop style window, like for a mission style door, in the upper part. The door is a traditonal type 6 panel door with the 2 upper panels smaller than the rest. The door itself is fiberglass i believe.

Basically cut out the hole, pop in the glass and cover the edges with trim.

My biggest problem is finding the replacement glass used in those kinds of doors.

I'm looking for glass that's Not clear.. something opaquish, hopefully leaded.. maybe a design etched or cut in it like fleur de lis or heather or whatever. I need some sources.

Also, is there any problem doing this to a fiberglass door? Thanks.

Correction: When I said "..smaller 3/4 arch top style.." I meant
"..smaller 1/4 arch top.."
like might be found in a craftsman or cottage style door..

So maybe i'm fraction challenged.. it's probably 1/3 lite with arch top.

You'll have several challenges here and I think you might be better off finding a new door than trying to modify a fiberglass door so radically.

First glass in the door needs to be tempered for safety. I don't think you can etch tempered glass after it is tempered, but I'm not a glass expert, nor do I play one on TV.

Trying to cut a large hole into the door and inserting a glass panel will present a huge challenge. If you look at a fiberglass door with a half light in it the light is held in place by trim that screws into itself and basically clamps itself to the door. It isn't screwed or nailed into the door as you would do with a solid wood exterior door. In between the fiberglass shells of the door is a some sort of foam insulation which would have the holding power of Styrofoam. You might be able to buy the half light window for your door and modify it, but I'd bet it would cost nearly as much as the door.