Reply #20: i buy cheep white sheets..

[flyarm]

and spray paint and cans of paint and i out line with magic marker ( make sure you put plastic underneat..a drop cloth as paint will go through....i have an upper deck..but i have done out of top floor windows as well..but i use those plastic ties and i attach to whatever i find...now i tie something heavy in bottom corners.( i am using large batteries..so it weihs down the bottom in wind..but i gather fabric in corners and use plastic ties and make a pouch and put battery in it and tie with the plastic ties..
i usually spray paint the letters and then go over it with real paint..water proof paint...with a paint brush...a wide paint brush..

its simple

i have also used white plastic table cloths..( cheap ) with the fiber stuff on inside ..it weighs it down in the wind!!

good luck!!print real big though so drivers can read easliy!

fly