Nottingham-Spirk Design Associates transformed Dutch Boy paint cans and invented the first Swiffer vaccum cleaner. But it has gradually made room for health-care products. “About 20 percent of what we do is health care,” co-President John Nottingham said. Nottingham said that in five year’s he’d like to at least double that. “If we could get to 50 percent that would be great,” he said.