More companies are trying to get into the mask-making business, as hospitals and public officials scrounge for protective gear for medical workers confronting the coronavirus pandemic.

A Texas businessman, a company that makes pee pads for pets in Virginia and a longtime medical-supply executive in New York are all buying machines or retooling production lines to make medical-grade face masks. However, the new entrants are facing the same problem as established mask makers: shortages of key supplies and equipment.

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