>>1764614I literally use soil mounds full of bricks, logs and other waste and tamp it down.
Makes compost and if you ever want to change the shape of your garden well it's just dirt rather than cut-to-fit bits of wood or expensive materials such as lots of bricks. you can just move it, simples. Plus you can grow in it for even moar space!! If you place them strategically you can use them to increase moisture levels by encouraging dew formation from the air.