Some manufacturers and supplies offer customized postal tubes as per the customers’ exact requirements. Large sheets of cardboard and thick sheets of paper are cut into thin ribbons. They are spiral-bound and measured and cut into the tubes. Water-proof and water-resistant postal tubes are used for heavy-duty applications. One can look for the tubes that are resilient to humidity and can withstand high pressure and temperature. As cardboard is porous, the tubes can be used for various purposes.