(FORTUNE Magazine) – Construction took just 15 days, and Loudoun County, Virginia, now has its prefab, six-cell, 23-cot jail in place and ready for its first tenants. Surfside 6 Industries of McClean, Virginia, made the hoosegow from converted shipping containers and charged $96,398 to install it. The company is now looking for more business. The U.S. assistant attorney general for justice programs, Richard Abell, thinks these buildings will do for jails what the Model T did for cars: ''It's a great boon. It's a Henry Ford assembly-line concept of prison construction.'' But J. Michael Quinlan, director of the Federal Bureau of Prisons, worries: ''People looking for easy money are buying up containers and peddling them to correctional administrators. I think Loudoun could have used more economical structures.'' Either way, the U.S. is desperate for new prison space. Providing it is a strong growth industry. Meanwhile, Captain J. K. Longerbeam, Loudoun's chief correctional officer, is content. He thinks the work-release prisoners who will be moving in will find the new place ''homely.'' J.L.