Scribing to level
When I make stools, I always leave the legs about 1/2" overlong for leveling. Then, after the final glue up, I trim all of the legs to make sure the piece sits true. To mark the legs accurately, I place the stool on the flattest surface in my shop: my table saw. (When I installed the saw, I shimmed it so it was perfectly level.) To level a stool, I place a 24" level on the seat and shim under the legs until the bubble stays in the center. Then it is a simple matter of scribing around each leg with a pencil and trimming to the line. To aid with this, I cut a v-notch along the center of a 7" length of 1 × 2 and lay my pencil in it. Then I slide the 1 × 2 around each leg keeping the pencil’s tip in contact with the leg to draw the scribe line. Once I’ve drawn my lines, I trim each leg with a hand saw.
