You can plant succulents in almost anything. Because of their shallow root structure, you don't need a very deep pot. You do need good drainage though. I took a large nail and hammered so many holes in the bottom of this box, that by the time I was done, it looked like Swiss cheese.
Because the metal is pretty thin, I made sure to punch the holes with the metal sitting directly on the ground, so it wouldn't bend.
I also lined the box with plastic, so it wouldn't rust as quickly. I then filled it with a potting mix specifically designed for cacti and succulents. I packed the box full of plants, putting the ones that I knew would drape, near the edges, and the larger plants near the back.
The box sits in full sun, and I water it enough to keep the soil moist, but not wet. I'll bring it inside in the late fall and keep it in bright, indirect light. In the winter I'll let the soil dry out completely between waterings.