can't tell the pattern but it's called pierced wood molding.
Search for it, many sources, multiple patterns.

This is probably an original cornice detail in cast plaster. It is probably a combination of "run in place" and cast pieces. The linear part was probably run right on the ceiling and wall by building up wet plaster on the ceiling and running a wooden/metal form over the wet plaster on a guide or "sled" to shape it. Then the cast pieces would be added with wet dabs of plaster.

There are people that can do this, particularly on the East coast, and there are two companies of the top of my head, Fischer and Jirouch and Felber that make ornamental plaster for architectural detailing.

I had some linear cornice duplicated and repaired where it was missing in one room in my apartment. (They now do it on a table, with reinforced plaster and a core of styrofoam to lighten it, and screw it into place and fill the holes.

It is EXTREMELY expensive to get complex things done, even my simple cornice was expensive, and I costs by the Linear Inch. Literally, not by the foot, by the inch. I would plan in the five figures per ceiling.

http://www.decoratorssupply.com/store/main.aspx?p=ItemDetailOptions&item=3495

http://www.decoratorssupply.com/store/main.aspx?p=ItemDetailOptions&item=3412

http://www.decoratorssupply.com/store/main.aspx?p=ItemDetailOptions&item=25109

http://www.decoratorssupply.com/store/main.aspx?p=ItemDetailOptions&item=1228

Not exact, of course, but in a similar vein.
Casey