I know there is alot of different ways to make a letterbox.
I need advice on what materials to use for a sturdy wooden box. Thanks in advance
Welcome to the Bunnings Workshop community @Ngarie. It's a pleasure to have you join us, and many thanks for your question about creating a street library.Some suitable and sturdy materials I could suggest would be Tasmanian oak, which is a hardwood, or marine plywood. Both of these would then need a good couple of coats of paint to seal them. I'd tend to stick away from softwoods like Pine. However, you could use H3-treated primed Pine.
I'll be looking forward to following along with your project. I've actually just finished repairing the door on a local street library that some vandals decided to destroy the other night. Please let me know if you have any questions.Mitchell