I don't know of any plans to help you out with but why not try designing one yourself on paper and then add in fun new feature you wouldn't find in a normal mail box. Something a kid would just love.

I don't know about the plans, but I do know that bark cladding is excellent for projects. I made my grandson a tree house that I got from a local bark siding manufacturer. Don't know where you live, but they do deliver and you probably wouldn't need much. It's extremely durable and nice looking.

Check it out at: http://www.partonbarksiding.com/quality-poplar-bark-siding

Anyhow, did you try You Tube? I bet there's an instructional video posted on there somewhere. I used it just the other day for fixing my truck. They have instructions on how to do just about everything.

Hope I helped.

-Richard

i don't know about the ones you see outside of a post office, but i remember when i was a kid, my parents gave me their old mailbox and they put it in the ground for me in the backyard beside my swing set. that was so much fun for me!