He had built the structure with rough cut lumber and fashioned it with a wood plane. He had used tin where the structure may be weak.
In the cracks of the wood he pounded nylon material that has been rolled to look like a rope. He pounded the material in to form a leak proof bottom. If he has enough resources, he will use a tar substance to give it more longevity.
I have seen and used tools like these that I got from my Grandfather Hadlock. They look good in the picture, but they are 50 plus years old. They are in great condition and the plane had an incredibly sharp blade.
This life is not easy and they pay a price from exposure to the sun and weather. They age before there time and life expectancies are not anything like life we have at home.