Do you know what these are called and for what purpose or use they are intended? Quality wood construction.?

I think you are right about these being used to make blue prints, but they wouldn't be needed with modern blue printing machines. Modern machines just involve feeding the drawings through a series of rollers. The first one exposes the drawing. Then you peel off the original and the next couple rollers apply thin layers of the necessary chemicals to the diazo paper to bring out the blue image. But the old fashioned way was more like hand developing photos. After exposing the drawing onto the diazo paper, you need to wash the paper in the chemicals to bring out the drawing. If I was dunking 24in. by 36in sheets of diazo paper in chemicals, I would want tongs like those. They'd also help reduce hand prints and smudges.