We built these garden beds from jarrah end pieces from an auction. They are mightily heavy. My Son (Rustikman) built them after I modified and took ideas from the Tall Man Raised Garden Bed. The actual garden bed is 40cm deep, the bottom board covers the base. He isn't a carpenter but did a beaut job. We have a few finishes to do and then in goes soil. I will put rough bark mulch in the first layer then some pea straw. Lucky we live near Bunnings, he needed an impact drill and new drill bits for the jarrah. He planned everything and made templates for drill holes etc. We pre drilled then put in screws. The posts were from salvage and not square and many of the boards were either shorter or bent in places but its a garden bed and they look terrific. This site has been so helpful for ideas thanks @mdstorrs and @Jason. will post again when in place and filled.
