So I finally got around to making one of these raised planters from repurposed fiberglass tubs. I got the tubs from a neighbor. I think they are from utility truck beds. 12"x12"x 3ft and 4ft. I got 2) 3' long and 2) 4 footers. Here's a pic of a 4 footer used as an engine cover for the splitter. I used a 4 footer and started making a base. The short sides of the tubs are not 90° it's a rhomboid more than a rectangle. That made it a little more difficult to make the frame. But I did it. San marzano tomatoes in for test fit. And fully skinned with boards and filled with those same 4 tomatoes.