Patrick "helping" out.
Anyway, the roof was dry after spackling. I was asked by a fellow blogger (Audra at Honey I Shrunk the House!) why I spackle in the first place and not just paint it. Well, you definitely could just paint the cardboard (I suggest sealing first so it doesn't absorb too much paint), but spackling gives it a crumbling effect after the aging process. If you're going for a new metal roof look, just seal and paint.
First, I painted the roof Raw Umber by Americana acrylic paint, not worrying too much about getting full coverage as most of it would be sanded down. This is what it looks after intense sanding with an extra-fine grit sandpaper:
After sanding, vacuum and vacuum some more. Also, wear a mask while sanding. You do NOT want to breathe this stuff in. Don't worry, no animals were allowed near the project during sanding and before clean-up.
I liked the result, and you could just leave it at that, but I wanted my roof to look SUPER aged. So the next step was to add stain (I used Minwax Wood Finish in English Chestnut). I took a Q-tip, soaked it in the stain, and pressed against certain portions of the TOPS of the panels. This was to make the stain slide through the grooves. Add more stain in certain area to make it appear natural, but be careful to make sure the stain doesn't run too far and onto your floor or project. This was the effect:
The stain gives the appearance of rust spots which are a part of almost every aged metal roof. You may think I'm done, but oh no. The next (and final step) will be to add bits of "debris" and greenery.
Disclaimer: These pictures are probably completely out-of-focus because of my DayQuil induced state.