I AM going to do this one!!! Take an old filing cabinet - take out drawers - put castor wheels on bottom & possible a wagon handle & voila... either a cute metal planter OR a wonderful pull-behind potting garden cart!
DIY Vertical Planter Garden. Something I would do differently, or add to it, is support under each planter. I worry the weight of the dirt, water, and plants will eventually concave the planters. Adding one more piece of wood (obviously cut into proper lengths) wouldn't cost that much more for a little more security.