We needed to connect both the containers. The opening has to be quite large and roomy but able to allow the containers to be secured and able to be transported without the shape being affected. A design by Jeff and a trip to the steel shop resulted in a design for a wide door that will swing open and stow out of the way for everyday use, but will bolt in place when we move the container.
This task was bigger than it looked but it turned out well in the end. We re-used the steel from the hole to make the door that filled it.