I changed the stool pattern posted previously to add a carving. If you use this I would go a little shallower on the carving.
Also the second file is brackets I laid out for the stool. There are four 'cause I am making two stools. The spiral carves on both sides and uses the 90 degree bit.
Home Depot sells a knotty pine glue up in 24" x 48" size for 16 bucks.
Got two stools and change out of the one piece. Seat was made to 7" x 12" with my grandsons names Centerline carved in it (love that CL).
Andy