I have fun imagining how I can use various discarded items as planters. My favorite was a pair of my husband's work boots. Having been owned by a man, these boots were well broken in, and ready for the landfill. I opened them up (you can leave the laces in place), and filled them with soil. I happened to plant chicks 'n hens in them. They are still in my garden biodegrading, and covered with chicks, for who knows how long.
You can cut holes in the toes for additional planting possibilities. I hope to find another pair at garage sales this summer, to paint white. I'll put some allysum in the toes, and vinca vines draped around the cuffs, with maybe red geraniums, or petunias coming out of the top.
Now, if you're familiar with "pack boots" (they are usually constructed of green rubber). These make good substitutes for those long, hanging, plastic planters with holes cut out of the sides for plants with runners (like strawberries, or spider plants), and I've also seen them done with impatients. Just fashion a hanger using the eyelets, cut some slits in the sides, and toes, and fill with dirt. Arrange plants in the slits and tops. Or put the parent plant in the top, and open the slits up for the anticipated runners. Voila!