Two hundred volunteers showed up last week to build a racing-themed playground in six hours at the YMCA of Greater Nashua's Camp Sargent, in Merrimack, N.H.

In the first week, about 300 children have used the 6,000-square-foot play space, whose design is based on drawings by children who attend the camp, said Michael LaChance, chief executive officer of the YMCA of Greater Nashua.