I live in an apartment with fairly big balconies, nevertheless, I'm always trying to get big planters suitable for my space and I came up with this easy solution. (Which also happens to be cheap)
It's a planter. Made out of a box. Easy as.
Step 1: What you'll need...
-A wooden fruit box. (You can go to the market, ask nicely and they'll just give them to you)
-Any type of plastic. (I used a black thick plastic sheet I had at home, but plastic bags would work as well)
-Staple gun (+ staples, d'uh)
-Plants, seeds, cactus or any type of plant or veggie you want to grow.
Optional--> Give some color to your box!
Just paint your box any color you want. It doesn't have to be perfect, just have fun with it.
(Remember to use some newspaper under it to prevent paint stains)