Suppose we apply "borders" and "2-dimensional" but leave the rectangular item for a while.
If we go the craft realm we could look at say, a round or oval shape; for example: a plate.
This morning in my ceramics studio I moved from my customary ceramic square tile, to a circular plate which I wanted to decorate by applying glazes, with brushes and sponges. It's really not fudging to say that it is virtually a 2-dimensional format.
Around the round edges, of course, a plate gives one the opportunity to choose from among a myriad of borders. Withe the help of a couple of artsy-craftsy stencils I sponged patterns around the border of the plate, interspersed with the word "Believe", which is one of those current catchwords that seems to be popular at the moment, and it suited my fancy. And in the center of the plate one can paint a vignette, or a landscape, or perhaps a sunshine face, which is what I did. Now it's ready for the fire, and here's hoping it turns out sunshiney!