This guide will tell you about the many combinations of armor you can put on your vehicle to make it stronger, divided in sections from Bad to Good. Each armor will be categorized in Protection and cost. These are my discoveries and are not based on proven methods and fact.
Armor Types Guide
Bricks, Scalables and Brick Reduction
This can go without saying for most, if not all of the BR community. Normal Bricks are not good in combat. Often they can be disconnected from other bricks with a single RPG shot and will increase brick count a lot. The vanilla bricks also do not look well aesthetically, with studs sticking out farther than my morning boner.
1x1x1 vs 1x1x 1s Scalables
Now, some of you less advanced players may be asking, what the hell is the deal with all the ones and the 1s? Well, anything with a 1s at the end is classified as a plate. These are the bricks that, when three are stacked on each other, create the height of a normal brick. The 1s scalables are not good for armor. When stacked on one another, they will simply give the same protection as a normal scalable at greater cost. A normal scalable gives more protection at less cost, so use a normal scalable over the 1s scalable whenever you can.
Why Are Scalables So Strong?
Scalables get their strength from the amount of possible connection points they can have. If a scalable is connected to more points on something, the bricks connection becomes stronger and harder to break. Although you may be thinking, "More scalables equals more protection", That is not the case. Say, take one large scalable platform and put multiple bricks clipping into each other. That will only increase cost and brick count. Instead, take one scalable that covers the space the other bricks did and divide it into at least 3 sections. That will give the main hull of your vehicle the most protection.
So you have a basic Idea of what you want your vehicle to be and what you want it to look like, but it seems a little pricey to make. Always use scalables. Because they can be scaled to your desiring length, width, and height, they are perfect bricks for making anything. If you want it to look nice, you can use scalable triangles, cones, and vanilla bricks to get some details, but it is not recommended as it will increase brick count and cost. If it is absolutely necessary, you can use normal bricks or more scalables than you need but always try to use them when you can.
Bad/Meh Armor Types
When your vehicle has armor that is a single material. This armor type, no matter the density of the material, it will make your vehicle a bit weak. You can strengthen the armor by copying the bricks and attaching them to the same point, although this unnecessarily adds brick count and cost and only increases protection by a small margin. Most vehicles for battle use tungsten as the main material, almost entirely too. These vehicles are usually vulnerable to AP cannons, stacked HE cannons and will almost always have some sort of weak spot where an RPG can take it down in one or more shots.
In my experience with Spaced Armor, I did not find it to work to well. Maybe I was working with and using wrong, but I have no idea. Spaced armor should be a good armor type because of the connection points, right? Well, it's complicated. If you connect Scalables by 1s bricks and zylinders, it condenses the armor so you save on space. This is a good feature until you realize that it sets the scalables at an awkward alignment, often preventing symmetrical side plates unless you have at least 4 plates. This type of armor is also usually fairly expensive unless executed correctly. The armor protects well against Armor Piercing projectiles, like the HMG and Ballistic Cannon shot. High explosive munitions however will most likely knock off the plates, one by one.
Mediocre Armor Types
Layered armor is armor made up of several layers of bricks, the bricks used are typically 1s scalables, but they are not recommended. Accompanied by other scalables and bricks, it becomes a very well-rounded armor. 1s scalables may save on space, but it adds on to cost and brick count and it's the extra connection points that make scalabes so strong. This type of armor is often only seen covering the front of a vehicle. It is resistant against HE projectiles but may have a little trouble with AP cannons. This type of armor is a nice all-rounder despite being expensive.
Good Armor Types
Armor that is made up of more than one material. This armor type is usually fairly protective. For the best protection, a combination of Tungsten and Copper will do the trick. It functions best when You make the main body of the vehicle out of tungsten, but make the slopes and outer details copper. The armor type works well against all forms of attack, but is a little susceptible to AP shots. RPGs and HE cannons will have a tough time with the armor, being almost impenetrable by explosive ammo.
This armor uses the 4x2x4x Zylinder as protection. This can function as both armor for the vehicle and protection for the driver. The Zylinders protect well against a modern conquest environment, dominated by vulcans and stacked guns. This type of armor combined with the Multi-Material Armor can make you or your vehicle nearly invincible.