I just got a sheet of plywood cut it to 6x4 and nailed some molding to the edges to make a frame / dice fence
watered down some wood glue sloped it on and pored a bag of children's play sand (the cheaper the better) over that let it dry over night. Sprayed to brown then dry brushed it with a lighter brown then very lightly with some bleached bone where i was not going to flock with some cheep woodland seenicks flock of a few shades and put it up on some saw houses. its not the easyest / fastest way but it took my friends and i a weekend to do and has lasted about 10 years so far with little to no damage a few minor chips when people droped there figure cases on it and the glue had not totally soaked the sand but i fixed them a little wile ago with about 15 min and a few brush loads of paint. not a big deal