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I used a dulled awl to "draw" the raised seams from the bottom or baking side of the material. It is soft enough that a firm uniform pressure makes a nice line when I used a square as a guide.
I distorted the material when drawing the lines on it so that it did not want to lie flat. I needed to glue it down. I used waterproof contact cement which seemed to work quite well; but as it was cold (no power-no heat) when I did it, it came unstuck...well only partly unstuck. I was able to peel it back a bit and brush in some more glue...we'll see if it works, I guess I have enough flashing to try again.
by the way, the building in the background of the previously posted photo is roofed with ice and water sheild. this roofing underlayment was coated with grit to make it less slippery. It lasted over a year on my house in Connecticut without shingles on top and kept the house dry. I had some extra and it seems to work well on models too. I have yet to find more. it is expensive, about $100/roll, but that is enough to do about 30 scale houses!