well i use ply wood for a few bunkers and cut angels on them so i can get use to using doritos on sup air you know for holding in your hoppers.... I also use barrels so it gives you the effect of actually playing something like a sup air bunker. heres a pic of myfield i'll only post one cause i made a thread on mine already
In my pasture I waint until a storm comes (happens often) then pick up all the 3" or larger diameter limbs and stack them ontop of each other braced by another tree works great. But using an axe to cut think green wood down to size isnt very fun. Works and looks great.
my favorite bunker types are "snake" bunkers- several sheets of plywood although one can use anything lined up in an elongated M shape it offers protection from several sides and can be useful when moving up the field- just thought id share