For this instructable you need an cnc router. Not everyone has access to a CNC machine, but if you look around you normally can find a shop not too far away. You can also visit a fablab with a CNC machine near you.
Step 1: Collect Your Piece of Plywood or Concreteplex.
The concrete plex in the picture is collected from the bins on a buildingspot nearby. And it's a good idea to ask the supervisor for permission, in my case they were extremely helpfull and even saved some for me.
The bigger the piece the larger you can make your barstool, thickness is not really of importance as you will see in the next step.
Step 2: Prepare Your Drawing File.
in www.stretchsketch.com you can modify and customize the barstool to your liking or to make it fit the sheet of plywood you collected in the previous step, just use the sliders on the left hand panel. Don't forget to modify the sheet thickness and the milling-bit radius, as this will save you lots of time when preparing the file in your CNC-Router application (like V-Carve Pro).
Press Download.. and proceed to your cnc shop..
Step 3: Mill and Kick.
Prepare and start the CNC router, and wait..
Take out the pieces and press-fitt/kick them unto the stool.