Updated on Sept. 18 at 2:15 p.m. ET
At the beginning of the coronavirus pandemic, there were lots of stories about scrappy manufacturers promising to revamp their factories to start making personal protective equipment in the U.S.
Back in the spring, fuel-cell maker Adaptive Energy retooled part of its factory in Ann Arbor, Mich., to make plastic face shields. Now, 100,000 finished shields are piling up in cardboard boxes on the factory floor — unsold.