The General Motors metal stamping plant in West Mifflin closed yesterday, idling all but a handful of workers.

GM spokesman Chris Lee said the plant produced its last part on Nov. 20 and finished its processing work yesterday. All workers were laid off except for a small number of skilled craftspeople, who will remain on the job until mid-January, when GM will auction the plant's equipment.

The automaker had announced in April that the plant's days were numbered, following the collapse of a deal to sell it to Allegheny Holdings, one of whose leaders was retired GM executive Thomas Brady.

The plant's roughly 350 maintenance and production workers, who are represented by United Auto Workers Local 544, have been through a series of ups and downs that began in November 2006, when the automaker announced that the West Mifflin facility would be closing in 2007. That closing was postponed while talks were under way on selling the plant to Allegheny Holdings.

Mr. Lee did not know how many workers lost their jobs yesterday. Some workers will be recalled to assist in next month's auction, he said.

The plant has been in operation for 58 years and most recently had produced fenders, doors and hoods for the Chevy Cobalt.