One of the more popular ways of making a mason bee nest is to use 6" cardboard tubes with paper liners slipped inside them. The female builds her nest by filling the paper liners. To harvest your cocoons, remove the liner from the tube, and then tear open the liner to remove the bees. The cardboard tubes can be refilled with fresh liners for the next season. The beauty of this setup is that it allows easy reuse of the cardboard tube for the following season.