I have several weird structures that I would like to showcase. All of these are my own creations, however some of them may have been thought of before. Eitherway, most people should be able to find something new here.
1) Novelty block motars
It's pretty self explanatory how these work. To fire, just shoot one of the SLAMS. If you want to play mind games by launching dead carcasses, then simply jump on and give the block a nudge.
2) A fort design
This large but messy fort has many unusual design features. Unfortunately itook me roughly an hour to build (I really should be studying).
This fort provides quick easy access to your flag for two reasons: A to help you return the captured enemies' flag, and B to temp people into trying to steal yours. Thanks to the extremely long tunnel the enemy must travel down to escape with the flag, any attempts to steal it will just make you rich. Above the ultra long tunnel (with a roof designed to maximize the enemy's vulnerability) you have a platform to rain hell down upon them. This platform can only be reached from your spawn point, and is covered from outside fire. This means if the person inside the tunnel kills you (unlikely considering they can't dodge fire), you can keep respawning and trying over and over again. In short, they won't escape.
3) Block aligner
This is how I aligned all those planks, in the above fort, at a neat 90 degrees.
If you are a map maker, please include built in building aids. Simply slide the block in, then pull it out.
4) My style of bunker
You're probably looking at the below picture, and thinking "OMG ITS TEH SHITSORE". Well consider this:
- It provides excellent cover. Simply walk in, crouch, then shoot through the slit. You will have an excellent view, yet very little of you will be exposed.
- Its simplicity makes it quick to make. You can make whole walls of this.
- It's fairly nade resistant, especially when it's above the ground. Grenades simply slide out.
- Enemies can't use it against you. Occupants are exposed to your side, yet sheltered against the enemy. If the slit is above head height then the enemy cant stand on the other side and shoot throu

^ I suggest you always add one or two towers at half way. They are bound to be useful, and won't cost you much build time.

^ the multi level version
5) Mined planks
Rather than leaving mines along walk ways, try leaving them underneath a loose plank. They are harder to spot this way, and usually get more kills. It works especially well on fake entrance ramps. Just make sure the mine is aiming at the block, not placed on the block. WARN YOUR TEAM MATES!

One other mine trick is leaving a mined standing space inside a tunnel. Since few people hold down the crouch key all the way through, once they get to the standing spot, they will accidently stand into the mine (even though the laser beam might go in one ear, and out the other, the top of their cranium will still set it of; Ouch). These are harder to see.
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Hope you liked them!