i got the same problem. if the area is pretty heavily wooded (my favorite type of paintball field, especially if your neighborhood authorities get in on it, plenty of place to hide! jk of course) uhm but if its wooded you wont need much at all. i recently moved and ive been saving up boxes. if i were to make a field ( which i might be doing soon) i wld get a box and fill it with dirt or whatever you have available. also if you have old furniture that your parents wldnt mind you shooting up. if you have a local junkyard, it'll be heaven for bunkers. if you have an old matress stick it half way into the ground and use it.
