My brother took the idea I had and he and Steven put together one of the front porch planters today. He cut the side slats first so I could stain and paint them. I bought 15×15 plastic plant pots to set into the planter. Here are a few pictures of us putting one together today. I still have to stain the top and feet. When I put the other three together I will take pictures and a tutorial on how we did it. Everything but the plastic liners was leftover stuff from other projects. I paid $24 for the liners at Home Depot. The side slats came from when we had to cut porch boards down to match the existing porch board size. The other pieces are left from misc. projects. The paints, stains and wood screws were leftover too.
***Update: sorry the pics are posted in reverse order. I am still trying to figure out the iPhone WordPress app. Anyway, here is our one finished planter installed on the front porch. It looked huge on the back porch, but it looks tiny on the front!