It’s amazing how simple this planter is, just a couple of cheap log rolls from the supermarket and some cheap treated timber from your local DIY store.
Dimensions are determined by the size of the logs on the roll and are not that critical. The first planter was made by screwing the log roll around an old plastic trough. The whole thing is then finished with a mitred frame around the top to make it look neat. Finally give it a coat of water based wood preservative, one that doesn’t harm wildlife.