Trotec Ruby®

When doing arrays in Ruby, it would be very beneficial to be able to input a boundary area as max extents to array within. For instance, I have a 12"x24" piece of leather and a 2"X3.466" patch. I need 48 total and have to calculate how many rows and column can fit on the sheet. If I could just input 12x24 into Ruby and either the program not let me array outside of that space or at least give me a visual square I could see I was going outside of, that would be most helpful.