I made these great window boxes a couple weeks ago, and I’m here today to share how to make them for yourself. If you did it yourself, how did you figure out what to plant and how to do it? Thank you. I’ve been waiting for these window boxes for two years. Here are the finished window boxes with the plastic planters inside. Nice DIY! These window boxes were so easy, I swear it was ridiculous. I used the leftover fence posts from my DIY shutters, measured the width of my windows and cut three pieces of wood to the length I needed: Then I cut two end pieces the width of the wood — five inches long. Or, if you’re really ambitious, you could start your own from seed and plant them in the boxes when the weather gets warm enough.