Take a piece of printer label backing paper (peel all the labels and borders off) and print your design on the "waxy" surface with an inkjet. You will have to use the printer properties if it's text to print it in mirror image. Now press the paper wherever you want the design. I have used this on wood followed by a light sanding for "patina" to make it look like an old painted sign.
Depending on the ink this may or may not work for candles, but it will work for nearly anything else.