I built my raised beds with pallets, cut them in half, and put three beds in a row. I am getting them ready for planting, so I have turned them into mini polytunnels. I got all the wood free from work.
Put 4 posts down the centre, and some cross bars along the top, then drape a heavy plastic sheet over. Fasten the edges to the wood with big clips, (I used to have a market stall). The beds are covered with the branches I lopped off the Leylandi at the moment, to keep the compost warm.
This one has 2 rows of uprights giving it more headroom. Behind it my home made mini greenhouse, it is standing up to the winds very well.
Rocky, the cat from over the road is a regular visitor, I will have to close the ends off when I have planted it up.
Ilona