Print out the block and measure one of the sides. Since this is a pdf file, it will print fine. Measure one of the sides of the block on the printout. Divide the desired block size (12.5) by the side measurement and multiply the result by 100. Then take the printout to a copy machine and use the resulting math to increase the size of the copy. For instance, if the side measures 8.5 inches. 12.5/8.5=1.47x100=147% copier increase size. This should end up very close. Some copiers may need some adjustment to the percentage.