Picture of Octagonal raised garden bed
Treated plywood
2x4s or similar
No more nails adhesive
Black plastic
Duct tape

Table saw
Screwdriver (preferably electric)
Staple gun
An extra set of hands or clamps
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Step 1: Cut the plywood

Picture of Cut the plywood
These beds are 1930mm (76") in diameter.
Cut eight pieces of plywood. I cut mine to 800mm x 300mm (about 31.5" x 11.8“). The size does not have to be exact as long as they are all the same. This picture shows wider pieces which made up the center bed of a mandala garden.

Step 2: Cut 8 pieces of 2x4s or decking timber

Picture of Cut 8 pieces of 2x4s or decking timber
Cut the joining pieces to 300mm or the same height as the plywood. I used left over decking timber.

Step 3: Set up the table saw

Picture of Set up the table saw
The angle between each of two piece of plywood is 135 degrees. Set the table saw up to 45 degrees and cut that part off. That is waste, use the 135 degree piece to join the plywood together.

Step 4: Timber cut on 135 degree angle

Picture of Timber cut on 135 degree angle

Step 5: Put adhesive on the timber

Picture of Put adhesive on the timber
Run a squiggle of adhesive on one side of the 135 degree angle of a piece of timber.

Step 6: Screw plywood to the timber

Picture of Screw plywood to the timber
Place a piece of plywood on the timber with the adhesive on it, screw together. Do this to each side of four pieces of plywood.

Step 7: Join sections together

Picture of Join sections together
After you have four sets of sides made up, follow the same steps of gluing and screwing to attach each of the other four pieces of plywood. Due to the large size and angles, there is no really easy way to do this. It helps to have a level floor such as a garage to assemble the parts on.

Step 8:

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One finished bed.

Step 9:

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Three in a stack.

Step 10: Wrap plastic around plywood

Picture of Wrap plastic around plywood
Cut long strips of plastic and wrap around, covering both sides.

Step 11:

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Using a staple gun loaded with short staples, staple the plastic to the plywood.

Step 12: Tape edges

Picture of Tape edges
We taped all the edges with black duck tape which isn't waterproof. After several years the tape has started to pull off. I just wait until dry weather, dust off the dirt and squirt adhesive onto it to re-stick.
cber10 months ago
How do u get to the center
rpjamess12 years ago
Fantastic looking. Makes me wish I had enough space to put a few together.
ClareBS (author)  rpjamess12 years ago
Thanks, three smaller ones would look nice too. Ours were originally going to be twice as big with a chicken dome and everything! Then we came to our senses and realized how massive that would have been.
These look fantastic! Much nicer than the square ones.
ClareBS (author)  jessyratfink3 years ago
Thanks! They were easy to make too.