My dear husband built me this raised bed a while back and it is producing beautifully!!! Size is 20' x 4' x about 3.5' and 10" deep. Actually I think he got tired of me complaining about the veggies dying.... our native trees are very shallow rooted (because we have almost no top soil on top of lava) so they travel long distances looking for nutrients and a raised bed on the ground can become particle board in no time. Roots even go UP into large pots.... This is so easy on my 72 year old back!!!! It's made with all recycled material except for the plastic liner....
Here's one 10' section
and here's the other half
In it are beets, chard (4 different kinds), kale (3 different kind) spinach, kolrabi, horenso spinach, yukina (the really really dark green leaves in the first photo), leeks, greenonion, basil, cilantro, parsely, asian greens, arugula and some strange greens I lost the tags for.