I cut up manila folders for these two on the trailers. The red one I cut out and folded the sides down, them curved around a dowel to make the three small curved sagging areas. The other is just a flat piece cut to fit except the edges are curled slightly which gives it both a bit of strength so it does not bend. I paint them with oil based flat - water base paint ruins the paper. The posts holding their ends up are just very thin styrene rod.
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