Such a flower bed among greenery looks good, as in the photo. You can install such a “train” along the garden path, or use it as a fence for a flower bed. In the latter case, it is recommended to carefully select the plants. This is done so that the flowers in the "trolleys" boxes with their bright color serve as a frame for the flowerbed and harmoniously combine with it.
The materials for such a flower bed are just a log and a few boxes. A semblance of a locomotive is made of log sections, wooden saw cuts are used as wheels, boxes can be knocked together from any of the boards. In principle, boxes made of another material are also quite suitable, the main thing is to keep the shape and make the flowers comfortable.