Without some kind of hi-tech watermark, modern technology has made faithful reproduction nearly impossible to avoid.
With a $200 scanner (relatively high-end, these days) our dye-sub printer at work, and a little tweaking Photoshop, I can make reproductions of highly color-variant photographs and diagrams that I can barely distinguish from the original, if I use the right kind of paper to print on. Many of these same tools, if they are out of reach for the home consumer, can be used for a small fee at a kinkos or similar print shop. Heck I once took a $1 bill, copied it onto a high-grade paper I bought at a specialty paper store, soaked it in water, and when it dried, it looked and felt enough like a real bill, I’m sure I could have passed it off in a supermarket without the cashier thinking twice.
Of course, I burned the reproduction, ground what was left into a talc-like powder, and scattered the ashes in Boston Harbor, in case any Secret Service agents are reading.