All maps have fortifications, but almost none last, or aren't very comfortable/useable. I often find find myself being yelled at for "Griefing" someones structure while trying to improve it. So in the past 3 or so days of playing the game I have come up with/improved upon some designs for 3 simple defensive structures.

----------------------------BATTLEMENTS---------------------

Battlements are a basic wall that stops enemy movement while providing the defender with a good vantage point. The best design in my opinion (which is already being used frequently) is the staircase.

http://upaoncp.files.wordpress.com/2011/06/aoswall1.png

Those who prefer crouching or who want reduced recoil from the machine gun can stand on the top, and hide behind the blocks sticking up to reload.

Others can stand on the second step or just run up the stairs and over the top. The solid wall is hard to destroy with grenades and enemies will be stopped by the vertical wall on there side, while you can easily just run over the top!

Optionally, you can maker this taller or smaller, or even add gunports lower down on the structure. (Credit to Chaos BR)

--------------------BUNKERS/GUNPORTS-------------------------

For any bunker that is ment to last, I suggest walls that are 2 or more blocks thick. To make an efficeint gun port through thick walls, dig out two blocks right above the floor then another one through the wall to provide the gun port. It should look like this.

http://upaoncp.files.wordpress.com/2011/06/aoswall2.png

The fact that it is only 2 blocks high allows you to not have to hold the crouch button to steady your machinegun aim, but does make it harder to get out of there fast when neccasary. To solve this issue, you may also dig out 2 blocks next to the port like this to provide some cover without having to crouch again.

http://upaoncp.files.wordpress.com/2011/06/aoswall3.png

-------------------------TRENCHES----------------

Trenches, though not that common are an excellent defense because they require no blocks, and you are less visible to the enemy.

An ideal trench, with all the bells and whistles would be similar to this.

http://upaoncp.files.wordpress.com/2011/06/aoswall4.png

The Machinegun nests can be placed at certain distances to provide a good method for sweeping away all the enemys infront of you.

The Second row is for those using rifles. They can crouch for a while, pop up, shoot, then crouch back down to relocate/reload. The 2 block high wall can be jumped over to charge out towards the enemy also (Bad idea if they have similar trenches)

The third row is for general transportation around the trench, whether to relocate, regroup in preperation for a charge, or run the hell away from the grenade next to you. Because it is 3 blocks deep you will not be visible from above.

-------------GENERAL IDEAS TO USE-----------------

-Make sure the area in front of your building is clear, even if its a teammates build!
If the enemy moves up far enough to use a teammates structure against you, they may be able to throw grenades into your structure. However if the area is wide and open, machinegunners can mow down anyone who approaches on flat maps such as pinpoint.

-Building these structures around your tent in a last ditch effort will be VERY good idea. A single Machine Gunner can reload instanyl and mow down the enemy at the same time.

-Think about what damage a teammate can do. Make it a pain in the ass to knock down your structure!

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If you have any suggestions on other good ideas, post them!

Sparknotes: A noob is giving you some advice on building stuff from what he has observed in a few days of playing on pinpoint.