You want simplicity and economy? These stools are designed so you can create eight of the short ones or four of the tall ones (or combinations thereof) from a single sheet of plywood. Here we’ll show you how to build the short version; the taller stool is a couple inches wider, but employs the same concept to build.
Rip a 24 x 24-in. piece of plywood into 18-in. and 6-in. strips, then draw "crosshairs" (Photo 1) to locate the center of the larger board. Drive a drywall screw in the center and use that as a pivot point for swinging a 7-in.-radius circle. Draw lines 3/8 in. away from the crosshairs on each side (Figure A) to create 3/4-in.-thick layout marks for cutting the interlocking notches and installing the leg brace blocks later on.
Drill a 1/2-in. pilot hole in the lower notch as shown in Figure A, then insert a fine-tooth jigsaw blade and cut out the round top. Use your jigsaw to cut out the legs and the 3/4-in. x 2-1/2-in. notches for interlocking the legs. Use a router with a 1/4-in. round-over bit to soften both sides of the top and legs except for those edges along the tops of the two legs (Photo 2). If you don’t have a router, ease the sharp edges with sandpaper. Cut the triangular blocks from the 6-in.-wide cutoff (Photo 1) and secure two of them to the underside of the top disc with glue and 1-1/4-in. all-purpose screws.
Slip the legs into place as shown in Photo 3, then secure them to the blocks using 2-in. screws. Add the other two triangular blocks and apply a finish of your choice. We applied sanding sealer, a dark stain and then a coat of polyurethane.