My husband and I built three 4'x4' boxes out of cheap lumber in the fall of 2012. We filled them with top soil, peat, and compost, over a layer of newspapers (to kill the sod below). We used longer pieces to stabilize the corners, and tacked up chicken wire to dissuade the bunnies (the long corner posts were also great for hanging light netting when I needed to protect seeds and starts from the birds). Here's the website with the instructions: http://www.almanac.com/blog/gardening-blog/raised-bed-gardening-cheap-and-productive