Balls should print at the correct size on the corresponding size paper when the printer is set to the correct size of paper. When printing be sure to select the correct paper size and do not request that the print be scaled or shrank/expanded to fit the page.
Balls will attempt to print up to the full paper size you request. Normally, printers can not print to the full paper size, which can result in your Balls being trimmed slightly on the shorter dimension if you try to fit the Biggest Balls you can in the space you have available. If this happens, and you don't like your Balls trimmed, you will need to select a larger size of paper.