I built my seat back in actual size using AutoDesk Fusion 360. It then let me export it to a “.stl” file, which is what most 3d printers use, but also the program Cut3D also uses this format. Cut3D lets you configure how your tools (endmills) make their way around (and through!) your material on the CNC router.
I had originally planned on making the seat back a two-sided piece using the ShopBot, which is why I made a jig out of plywood on the sides, then also made screw holes on each end. However, my free scraps of 2″x4″ weren’t actually 2″ thick. I’ve come to learn this is the standard for most wood. Instead of going back and re-creating my toolpaths I decided to just machine the one side, then do the other side by hand.
The ShopBot cutting out my plywood seat using the same file and setup as the jointed pine seat