It is a real mental puzzle, added to it, an octagon tower on the end of a square room. I started in the center and spiraled out. It took about 4 days, each other end is reversed by cutting a grove or adding a spline to the T+G flooring. I kept the little shaper there to run the grooves. The last of three board would get the groove where the marble went only in the middle. The marble is set on a plywood square planed to made the marble flush. All the wood was prefinished seconds from a local flooring plant, they sell 3/4 walnut for $2-3 per square foot and the defects are hard to find, some have reversed ends, a bubble in the finish or planer nick. Since I was cutting them shorter, it did not matter and there were many angle cuts to the walls.