This is the easiest way I know of and use:
Do you have a smart phone? If so, turn on the flashlight app/function. Lay your phone face down on your work surface. Put a few pieces of masking tape over the LED light to dull it down a little -- enough so it doesnt blind you. Once youve done that, cut some fine line tape in a few strips a few mm wide. Place the canopy over the light. Now it should be easy for you to see the lines in the canopy. Use the small strips of fine line tape to tape out the boarder of the canopy frame. Once finished just used pieces of tape or making fluid to fill the centers. It's truly that easy!