Tiered garden beds are great for adding visual interest to a garden while also helping segregate different plants. This instructable goes through the step by step creation of my garden bed, but please take the basic ideas and expand. The design I used is fairly simple and symmetric but the same steps could be used to make an intricate abstract masterpiece. I didn't need a back to the boxes since it was up against a fence, but it would be easy enough to add those if needed.
While I have a decent amount of tools, there are certainly tools that would make this easier (a bandsaw could notch the ends with 10% of the work). Again, modify these directions to work best for you.
One last note is if you could get your hands on some old railroad ties, they would work great for this project as well. They'd add a nice green touch while slashing the costs of the project. Unfortunately, I couldn't get my hands on any.
The materials I used are:
11x Pressure treating landscape logs ($4 each at Lowes)
2x 10ft pieces of 3/8" rebar ($4.50 each)
Lots of dirt.
Reciprocating saw (with metal and wood blades)
Drill with 1/2" Spade bit
Step 1: Cutting the wood to size
Each of the 4 main boxes is 28" long, 40" wide, and two logs high. I chose these because each 8 ft log cuts into exactly two 28" and one 40" section. I recommend waiting until you have the larger boxes set before cutting the connecting logs as this allows for minor changes in placement later on.