In the bedroom, Chen Xin is leaning on the bed and using CAD drawing software on his laptop to design the door of the shelter.

When the system upgrades items or shelters, it can be modified according to Chen Xin's ideas, so Chen Xin decided to add a little bit of his own ideas to the door of the shelter.

As the first gateway to the Vault against the invasion of the outside world, and the strongest defense, the Vault's door is more than just a gate in Chen Xin's vision.

When the survivors discussed how to build a doomsday shelter before the disaster struck, they had put forward many plans for this issue.

The original plan was proposed by the big guy who made water purifier equipment, and he borrowed from the federal plan to rebuild a shelter with an abandoned missile silo, and proposed to buy an abandoned bomb shelter, and then transform it into a small shelter, and everyone lived in it together to form a small community.

In this plan, the gate of the shelter is designed as a protective screen door of the same level as the civil air defense project built by the state, weighing more than three tons of reinforced concrete structure wrapped in steel plates, plus supporting equipment such as poison filtration and air purification.

Such a gate structure is standard enough to withstand the shock wave of nuclear bombs, biological and chemical weapons, and poison gas in wartime, giving people an incomparable sense of security.

It's just that this plan was abandoned at the beginning of its proposal.

Without him, Yanguo does not sell abandoned civil air defense facilities, especially at this critical moment when the end is imminent.

Therefore, everyone could only follow the construction plan proposed by Chen Xin, find a mountain to dig a hole, and then fill in the specially customized container house to build a shelter.

Of course, the shelter built in this way is not as solid and reliable as the abandoned civil air defense project, but considering that everyone is not facing a horror like nuclear war, this kind of shelter is enough.

After all, what everyone has to deal with is nothing more than extremely cold temperatures and severe air pollution, which are much easier to deal with than nuclear radiation.

And the door of the shelter has been replaced with a three-proof door that everyone can buy, instead of the protective screen door that was expected before.

Originally, Chen Xin didn't have too much thought about this, no matter how he said the three-proof door, it was twenty centimeters thick, and if the two doors were locked from the inside, it would be difficult for a tank to tear down the two doors from outside.

But now that the system has been upgraded, Chen Xin feels that he can still make his gate a little stronger and more reliable, and improve his defense a little bit.

In Chen Xin's vision, he would add the current two three-defense doors to three, and renovate the corridor to enter the shelter.

The first door is naturally the outermost door of the shelter, and after entering, it should be a disinfectant room that can be cleaned and disinfected, and it should be used to clean and disinfect personnel and vehicles entering the shelter from the outside.

Although there is no such deadly thing as nuclear radiation in the outside world now, since he knew that the chemical plant had exploded, Chen Xin knew that the air outside was no less deadly than a nuclear bomb exploded in front of his home.

The toxic and harmful substances that have now permeated the air may not be as deadly as nuclear radiation, but if they are accidentally contaminated, in this era when medical conditions are far less than before the end of the world, the degree of death may still be above nuclear radiation.

Not to mention anything else, if you are drenched in acid rain, with today's medical conditions, unless Chen Xin makes a medical cabin that can repair body tissues, it can only be worse than death.

Acid rain today is not the same as before the disaster, and the most common thing before the disaster is redness and itchiness, causing allergies or lung diseases that require medical attention.

But now the acid-base concentration of acid rain is much higher than before the disaster, and if it is drenched, it will really corrode the skin.

After the decontamination room, Chen Xin planned to build a preparation room.

The so-called maintenance room is a place where travel equipment is prepared.

Chen Xin plans to put all the protective equipment that he may need when going out here, and move the garage up.

This way, you can get ready here, and once everything is ready, you can start from the training room without having to put protective gear inside the shelter.

This will both make room for the now somewhat crowded interior of the shelter and reduce the likelihood of external hazardous materials being brought into the shelter.

Between the decontamination room and the maintenance room, Chen Xin also plans to install another partition door to prevent harmful substances from entering the shelter through the air, and at the same time, he can install defensive weapons between the maintenance room and the decontamination room.

Although Chen Xin didn't intend to harm people, he still had to take precautions.

He is no better than the official shelter with all kinds of defenses, and the gate outside is not as strong as the official shelter, in case someone opens the gate, he must have some means of self-protection that can kill and injure the enemy.

The ideal way, of course, is to make a laser corridor like the one in the "Resident Evil" movie, where as many people as you come will die.

But this kind of thing Chen Xin is just thinking about it, and actually getting it is not that it can't be done, but that it is not cost-effective.

Therefore, Chen Xin's plan was to get a heavy machine gun in the direction of the gate of the shelter, and when an unidentified person or enemy came in, he would shoot directly, which was convenient and fast.

However, now that he does not have a heavy machine gun on hand, Chen Xin plans to use bows and arrows to convert them into bed crossbows instead.

In a sense, the use of a bed crossbow is even more powerful than a heavy machine gun, and the effect is better.

Even if it is transformed into a repeating crossbow, the lethality is also nothing to say, and the arrows can also be recycled and reused, which is highly efficient, energy-saving and environmentally friendly.

Thinking about it this way, Chen Xinxing's design drawings were almost drawn.

The first three-proof door is used as the gate, and after entering is the disinfection room, the disinfection room is connected to the maintenance room, and the middle is connected by a short corridor, and two partition doors are installed, and a repeating heavy crossbow is installed in the corridor.

After entering the maintenance room through two partition doors, you have to pass through a three-proof door to enter the corridor connecting the shelter.

At the bottom of the corridor is the last three-proof door.

With this kind of protection, Chen Xin feels that the safety of his shelter can be improved a lot.

In addition to protection, Chen Xin also plans to adjust the short-wave antenna and vents to the inside of the shelter, so as to avoid dangers such as the enemy cutting off his communications and poisoning the inside of the shelter through the ventilation duct.

Why don't you even adjust the structure of the corridor? Make a floor concealment door and add another layer of defense?

Chen Xin thought about it carefully, but finally gave up the idea, not that it couldn't be done, but it was unnecessary.