Here is a tutorial for a quick and easy, upcycled, CNC plywood sitting stool with a 14x14" seat and a 22" height. If you want to maximize efficiency and just go straight to cutting/assembly, I've included an .eps file to upload in VCarve Pro so all you'll need to do is add in tabs.
3M 2.8x4" multigrade commercial sanding sponge (or sander of choice)
Mallet or Hammer
Old Cloth/Paper Towels
Step 1: Illustration + Digital Edits
I've included the .esp file in this step so that if you want, you can download and use it to put through VirtualBox VM and VCarve Pro. Remember to add tabs before sending it on the CNC machine. I placed mine around all the main flat cuts so that it would be easy to chisel off afterwards. Note: I user tested my instruction set so I created two stools instead of one, however if you're using the .eps file included and only have material for a single stool, the file is editable on Adobe Illustrator.
I wanted to design a stool that was fairly easy to assemble and disassemble, but still aesthetically organic and clean. I looked to Dmitry Kutlaev's simple plywood stools for inspiration and measurements. To get a better sense of how the wood would fit together post-cuts, I created a digital 3d version in Rhino which you can see in the .gif, however this won't be necessary.
Step 2: Material Scrapping
For this project, I was set on using upcycled material and so I called out to local lumberyards and companies to source for unwanted plywood. I was able to find some options on craigslist.org as well as freecycle.org but ended up getting lucky at a lumberyard near by and was able to pick up a 3/4" 4x4 piece of birch that was slightly weather damaged from the rainy season. Luckily, the wood was nice and ended up being salvageable, however, the stool design is meant to be sturdy so most plywood will do the job. If the wood you use if not 3/4" make sure to go adjust the stool slots as necessary in the .eps file on Adobe Illustrator so that the wood fits correctly during assembly.
Step 3: CNC Cuts
This step took a little under 20 minutes to complete (the machine estimated closer to 40 min.) but this may vary depending on your machine. Make sure you've added tabs in VCarve Pro for the machine and you've nailed your plywood in place before starting the cuts.
After the cuts are finished, remove the nails from your plywood and use a chisel and a mallet to break the tabs to free your pieces from the remaining plywood. Try to chisel as close to your stool pieces as possible to minimize the amount of sanding you'll have to do later on.
Step 4: Minor Assembly
Each stool is three pieces, and assembly is simple, however you'll want to follow this step so the pieces fit together perfectly. First off, after sanding all of your pieces, you're going to want to take a hand saw or razor blade and make the slot angles sharper. Since the CNC machine bit is rounded, you'll notice the corners are slightly rounded--you're going to want them to be 90 degree angles so the edges of the wood fit in perfectly. As you can see from the first photo, I used the skinniest metal hand sander I could find to really carve out the angles.
Additionally, since the slots are exactly 3/4", the fit is snug. If you're having a hard time, try using a piece of scrap wood and a hammer or mallet to secure the pieces together.
Step 5: Oil Finish/Finishing Touches
This step is obviously not mandatory, but I used some Danish oil in "Fruitwood" for a natural, refined finish. I highly suggest you take it outside prior to oiling because the smell is potent. Just take an old cloth or some paper towels, and rub the oil into the wood in circular motions for an even coverage.
As you can see, the Danish oil just accentuates the wood like a nice spray-on tan before summer season comes around the corner. There are other finishes you can get that range the scale--however if you insist on doing a wood finish indoors, there are water-based finishes that won't make your home smell like a chemical plantation explosion.
Step 6: Finishing Stability Touches (Optional)
One of the stools I had assembled was still slightly wobbly when I sat on it so I took two 1/2" screws and put them into the bottoms of the feet that were slightly shorter. This will take some eyeballing to get right but you're just going to want to keep adjusting how far the screws are as necessary until your stool is nice and stable when placed upright on a flat surface.