It broke.
Our home when purchased had a planter box under the two front windows. I liked it, no problem, no concerns. Well ... it wore out over time and was falling apart. On top of that, I am in the process of re-designing our entire front entrance area, decking, fencing, landscaping, painting home, etc. Thus, a new planter box fit that need also. It was just time.
The design is pretty close to the original. I liked the original. But, had to fancy it up a little. And make it stronger. I put some extra support in the inside areas as that was the first thing to go in the old planter box. The top edging, a little more predominate than the previous planter box and I painted it white to match the trim treatment of my entire home repaint. Before, a simple blueish grey which matched the home exterior.
Not a difficult project but a nice touch. Pressure treated lumber to withstand the soil and weather. Screws to hold it together (nails in old one) and that's about it.