The original raised beds are now at the end of their life. The 1 1/2” thick boards were a mixed bag of a “builders sling” from Dun Lumber. I noticed that the primed cedar facia boards lasted the longest, in fact some of them are still in very good shape, the raw unpainted construction lumber rotted first.
This is what I came up with after reading page 48 The Woodwright’s Guide by Roy Underhill.
-- Love thy neighbour as thyself