I am looking to build a couple of indoor plant stands for an enclosed veranda area that will hold ferns and other plants that like to be heavily watered. I want to create a waterproof section inside the base of each stand to capture the excess water. I am hoping for a lining of some description that will enable me to line the bottom and about 100mm up the sides. The bottom is planned to be about 1.2m long and about 300mm wide.