If you want them clear, you could try drawing the lines, in a graphics program or in Excel, then having them printed on clear plastic. Most office supply stores today can do laser printing on "transparency" film, and since these look like black frames, it would be very simply to do.
For that matter, if you don't want them clear, you can spray the back side whatever color you need.
Years ago, I made roundhouse windows that way at work, by printing them on paper, then running a transparency sheet, for overhead projectors, through the office copier. Apparently some of today's copiers, and laser printers, are too hot for plastic, so I wouldn't try the boss's, unless you already know it will work.