There are many different sections that make up the Base of Operations (BoO), but one you'll likely be spending an excessive amount of time at is the Crafting Station. This is a location worked into the very core of the BoO, available from the start (though, possibly a level requirement I'm forgetting offhand) and not directly associated with any specific wing. As you may have surmised, the Crafting Station is where you are able to create various gear, weapons, and mods for your character.
In The Division you can craft items from the following categories: Weapons | Masks | Body Armor | Backpack | Gloves | Holster | Knee Pads | Weapon Mods | Gear Mods and the final section is for Material Conversions. Also, every weapon, piece of gear, and mod comes in one of five qualities (rarity color): Worn (White) | Standard (Green) | Specialized (Blue) | Superior (Purple) | High-End (Yellow). For crafting purposes, you'll mostly focus on Superior and High-End, avoiding the lesser quality items, which I will explain below.
In order to craft anything in The Division, however, you need to have blueprints (shown above). Blueprints come from a variety of sources, but the most common is missions and vendors. I believe they were originally planned to drop from NPCs and chests, but I don't recall ever finding one in this fashion. As you can see, each blueprint gives you the possible loadouts/rolls you will receive when crafting that particular item.
Unfortunately, besides hunting for blueprints, you'll also have to scour the city for resources to fulfill blueprint orders (Resource Requirements depicted in the lower left corner of the pic above). Scattered throughout New York City you will come across designated locations where you can find the following types of crafting materials: Fabric | Weapon Parts | Tools | Electronics | Division Tech, all of which also come in Green, Blue, and Yellow rarities.
You can also obtain all of these materials, aside from Division Tech, from breaking down/dismantling items in your inventory. It's important to note that you can convert materials — again, aside from Division Tech — from a lower to higher rarity. For example, Green to Blue and Blue to Yellow.
In the world of crafting, Division Tech is a particularly sought after resource material. It's used for both supplementing the other material types you may be lacking and crafting High-End items. While it may be awarded for completing missions, the major source of Division Tech will come from exploring the Dark Zone, where both NPCs and special loot crates drop it.
When I first began playing The Division, I wasn't sure how big of a role crafting would play. It's kind of hit or miss for most games. I came to find that it plays a major role, being one of the only ways to get some of the strongest gear currently available in the game. As I mentioned earlier, I would avoid wasting resources on lesser quality items. This is because, despite time restrictions some players may have, it doesn't take long to level in the open world of The Division. Following and completing the main missions should place you in the mid 20's, but if you also do encounters and side missions (an additional source of XP, currency, and items) you'll be able to hit the max level of 30 in no time.
By the time you can craft a specific lower level item, you are already surpassing that level, and finding drops better than what you would have crafted. Once you hit level 30, however, if you haven't been able to find some decent gear for specific slots and/or weapons it may be beneficial to craft. Otherwise, you will want to shift your focus towards High-End items and blueprints. And for some of the best, you'll have to enter the Dark Zone!
UPDATE NOTE: On April 12, 2016 The Division will receive its large Update 1.1 which will see changes being made to crafting system. Time will tell if crafting remains king!
What do you think about the game's crafting mechanic? Have you crafted any good items in The Division? What's your favorite item you've either had drop or crafted?