Cut 8 pieces of ribbon. The length needed for each piece, and in turn how much total ribbon is needed, is determined by the length desired for the finished piece.
Cut each ribbon section twice the length of the finished piece plus 6". Therefore, if an 18" cord is desire, cut the ribbon pieces (2x18") + 6"= 42" each.
Pro Tip: When using just one spool of ribbon for a one color core to use in later projects, cut the ribbon in four equal pieces of 7½ feet each. The resulting 8 strand braided cord will be approximately 21" long. Hint: To avoid the inevitable fraying on the ribbon ends, either cut the ribbon at an angle, put a bit of nail polish on the ends, or slightly melt the ends in a flame.