I would do them one at a time unless you want the look as illustrated or you want to miter the corners. You might also want to size the width of your borders using the Fibonacci number theory or golden ratio. Measure the width of your block and multiply or divide by 1.61. example: 9 inch block (division process) - 5.5, 3.5. 2.25, 1.25, 0.75 Any of these widths will give a balanced look. Just keep dividing the answer by 1.61 and round up or down to the nearest quarter or eighth inch as desired. Look up Fibonacci or Golden Ratio for more information.