I am in need of raised beds of higher volume, since I wanted to add some visual cover to my balcony. Plants need high volume of dirt to also grow in size above ground.

Also, I really like the kind of "framed" look the more expensive raised beds have. So why not construct one on my own? The total costs for one raised bed sum up to about 40 € (without paint and potting soil).

Step 1: Concept

The raised bed is based on a tub for mixing cement. The dimensions of this tub define every other measure.

The tub I was using was from an Austrian hardware store called "Obi" and was measuring about 70 (l) x 45 (w) x 40 (h) centimeters without its brim.
Using a pencil and a notepad, but also using SketchUp, it was easy to figure out that I would only need three different kinds of wood:

A: The wooden pylons. In my design they have a height of 1 meter each and measure 3,4 x 3,4 cm . If the raised bed should be lower, just adjust the height of these pylons.
B: Smaller wooden bars. These are used to mount the side walls to the pylons. You would need two of these for each pylon. Mine are just a little less high as the tub is, namely 35 cm. The reason for this is, that it was easier to cut all the needed pieces out of two single big bars. Otherwise I would have had to by a complete third big bar just to cut out one additional small wooden bar.
C: The side walls. Each of these is composed from 4 single pieces of wood stuck into on another. There are 2 x 4 longer bars and 2 x 4 shorter ones. The longer ones have a length of 70 cm and the shorter ones 45 cm. These are exactly the inside measures of the tub - you may have to adjust these values to your dimensions.

Step 2: Getting the Materials

So, lets grab the materials we discussed in the previous step!

The pictures show the single pieces I gathered. I also bought two different kinds of screws, one smaller the other bigger. The smaller screws are for mounting the wall bars, the bigger ones for fixing the smaller wooden bars to the pylons.

There is this great service at my local hardware store where they cut the bars you are about to buy into pieces of desired measure. I wrote the wanted lengths directly onto the surface of the wooden bars with a pencil to avoid misunderstandings. After waiting in line, the pieces were cut promptly.

Now I only had to bring them home somehow - I always drive by bike! :-D

Step 3: Building - Pylons

This is a very straightforeward step.

For every pylon you need to attach two smaller wooden bars. The best way to do so is, to

align one smaller bar like shown in the picture
drill three holes into the smaller bar (and maybe a little into the pylon, but not too far) to avoid splitting the wood when using the screws
mount the smaller bar to the pylon with three screws
repeat the steps with the second bar (as shown in the pictures)

This has to be done for all four pylons.

Step 4: Step 4: Building - Walls

To mount the walls, you first have to stick 4 of the single planks together and align them with the edge of one pylon. I did put the aligned planks beneath one pylon and drill eight holes (two for each plank) into the smaller wooden bar (see picture). These holes shoud be nearly as big in diameter as the swrews used.

Since the screws to fix the bars will be quite short, I also added countersunks with a bigger drill.

After that each hole was filled with one smaller screw. Since the holes were big enough for the screws not to get a tight grip, the wooden planks were pulled towards the smaller wooden bars when tightening the screws.
The best way to start is to mount the outermost screws first. By that you can assure that the wooden planks are squeezed in tight enough.

During work, my smaller screws ran out, because I built many of these raised beds. My solution was to take slightly bigger screws (which I had on hand by accident) and insert a washer to reduce the length of the screw. This actually resulted in a better grip then using the smaller screws and using no swasher - so in the future, maybe this is a better way to go?

This has to be done twice for each pylon, until the raised bed is complete!

Step 5: Painting

We want to use the raised beds outdoors. For protecting the wood from the weather and maybe also to give it a touch of class (although, I really like the natural look of wood, but it would not stay this way leaving it outdoors), I decided to apply an ebony coloured glaze.

Since this is a very dark colour and the wood is quite bright, it has to be applied twice. So plan in advance when you want to scumble, the paint needs about a day to dry bevor applying a second layer.

Step 6: Filling

Now we can put in the tub. It should fit nicely, if not, it can be squeezed in a bit.

We should not forget to drill some holes in the bottom of the tub to allow water to drain.

Next, it is up to you how you decide to fill the raised bed. I did lay in some planting fleece and added gravel. This ensures that the potting soil will stay inside but also allows the water to drain completely.

After that I filled the bed with potting soil.