there is also a junk yard near my house (this one family of rednecks used to own all of the property where my neighborhood is, like 100 years ago, so they put all of the old cars and tractors and tires and refridgerators)
really, anything someone can duck behind. make them different heights too, so some you have to lay behind and stuff like that. or you could set up some plywood walls, and cut a window in them and stuff like that
just talked to one of my paint crazy friends, and he said to go to a thrift store and pick up one or two of those hideous blow up lawn ornaments(for christmas or halloween..)
try to find the ones that don't need to be plugged in, then anchor them down.
i made a full 1 acre speedball course out of spools and metal roofing. perfectly semetrical at first but could move it around throught out the game if you wanted to it was soo much fun. For woodsball you can really use anything, cut down some trees, take off the limbs and make a pile of the logs. Dig sand bunkers if the soil is soft. We spent probably a total of 40 hours each with 5 guys making our woodsball course. just randomly after school when we were in HS go back and put in work. It was so worth it when it was done though. Damn i miss paintball sometimes
haha hire a bunch of mexicans to dig trenches....but seriously, a concrete pillbox like the ones at Omaha beach in Private Ryan would be incredible. Besides that, I love playing woods ball. The earthen fortifications are the best!
my friend had two sick places. one had two treehouses and also he layed wood up into y shaped trees so you could climb up.
he also had a speedball course that was portable, he just bought wooden stakes a few feet tall and bought some turf (that cheap ass green shit you can get at home depot) and nailed the carpet to them so they could roll up and everything, they were lightweight and did a great job. you could do this in the woods too.
another place we played at was just big carpets nailed to different trees and shit, with slits cut into it to shoot through.
build a few forts, then take anything you can get and put it next to some trees. dig trenches, litter the place with pallets, oil drums, plywood and big logs. Its all about being creative and finding cool, unique things to use.