Got PSP? Cheap Marston Matting from The Frugal Modeler, Hans von Cheapskate...
Wanting to do a "Marston Matting" or PSP hardstand for a Tigercat diorama based in Korea in 1950-51, I looked around the 'net for some and was shocked at the prices for what I'd need. I blew off the photo-etched almost immediately, then looked at the 1/48th Eduard PSP base and decided to get it. I looked around and found one on Ebay and won it for 6.00 with shipping... When it arrived, I found it was black styrene and the matting was nicely done, but I was rather disappointed as the courses were molded parallel to the long side, a mortal sin in diorama-building, and it was too small for even a P-51 at 9-1/4" x 6-3/8", much less a Tigercat... One COULD buy several sections and glue them together to make any size you want, but you need at least 3 for a Tigercat (or 6 for about any twin-engined bomber you care to name) in order to keep the entire plane within the "frame" of the diorama... At about 12-16.00 a pop retail, these aren't the best buy.
So I decided to do it better... I used aluminum foil, taping a sheet over the entire base as a "female" mold, and burnished the foil down with a piece of 3/16 squared wood dowel... I made three full-sized pieces and glued them down at an angle on a 12" x 12" piece of plywood that I had covered in a thin layer of sheetrock mud and sanded smooth. I sprayed the mud with clear acryllic varnish to seal it, then when dry, I used a spray adhesive to start glueing down the foil.
After I glued it all down, over-lapping a single course to keep the runs straight, I then painted it with Krylon "Moss Green". This gave it a good surface for washes and also more or less matched the color of the stuff as it comes off the truck.
I then started to wash it in black acryllic and rubbing alcohol, going heavier and darker than I usually do, and wiping off the wash from the high-points, letting it sink into the low areas and drain holes. After the wash dried, I shot it with more clear varnish, which darkened the wash even more for better contrast, then did a heavy dry-brushing of tan, rust and whitened Testor's Rust. Another coat of varnish and I added pastels, grey, brown, black, and tan, letting the chalk build up in the holes here and there to represent the places where the water would "puddle" and darker pastels in the "drier" areas.
And there you have it. A PSP'd hardstand, ready for the model and whatever extra weathering you want to do to it, and, with an initial investment of under 10 dollars, as big as you want to do it...