Bricks, railway sleepers and rocks, these are too ordinary materials that we can find on a garden bed border easily. But why not boost your imagination? Use recycled glass bottles,shipping pallets, clam shells and even logs to change the boring borders.
I'd use flowering shrubs rather than evergreens, a few different kinds, and arrange them in a reverse symmetry.] A long, thin garden with plenty of room for puppy to play and lots of privacy from the neighbours.