A seat or a small side table with a distinctive base that resembles a tree growing in every direction. Flat-pack design made of 18 mm thick ply parts that slide into each other. The 'twist-lock' mechanism is developed by Twistab.

Step 1: Download the Files

Here is an Illustrator and a Rhino file of the exact same stool.

Step 2: Open Files and Make Changes If Desired

Both of the files show a linedrawing of the stool. These lines are essentially tool paths for the CNC milling head. They are colour-coded and arranged on different layers. Each layer has a name specifying the cut strategy that a CNC machine operator will need to use. For example, "cut inside", "cut outside", "pocket 11.5 mm", etc.

You are welcome to modify the leg design and shape of the seat to your liking. The locking mechanism is developed by Twistab and they strongly suggest not to change it unless you know what you are doing!

If you're able to use Rhino, skip the Illustrator file and go straight to Rhino file. Otherwise you can start on Illustrator to tweak the design. When you're done, export your it as DXF file, which can be later imported to Rhino.

I must say I created too many "bridges" for each cut out piece, four to be exact. You can easily delete around half of them, leaving one or two bridges per cut out. FYI these bridges ensure your part is fixed and won't move around when the mill head is working.

If you'd like to make the original "Tree stool" design without alternations, then you can go straight to step 3!

Step 3: CNC Mill Your Stool

Send the DXF file to the CNC machine. A specialist will help to set it up for you.

The machine will cut four parts: legs x 2 + 'twist-lock' top + seat cover.

Step 4: Get Your Parts Out

When the machine has finished, take your four parts from the sheet of ply. This will involve some manual cutting or chiselling because of the small bridges were not cut through by the mill head. You will also see remnants of these on your parts. Cut these away and polish with sandpaper.

Step 5: Polish Any Defects (if Needed)

(If your parts came out fabulous from the machine, ignore this step and proceed to step 6.)

It happened in my case that as I was cutting away the bridges, top layer of the ply also cracked open and partly fell off. This left unsightly blotches on the stool legs. Do not despair. These can be smoothed out with power sanders. I was able to create interesting layering with that tool.

Step 6: Assemble the Legs

Slot the legs together into position as shown on the drawing.

Step 7: Assemble the Seat

The seat is comprised of two parts: the 'twist-lock' mechanism and top cover. Align the ‘twist-lock’ part into place and rotate it clock-wise till it locks (as shown on the drawing). Then add the round top cover making sure the pocket cut is underside and that it slides in the bottom part.