Armor Attachments are made by the Munition division of Traders.
The Trader's Reverse Engineering skill depends the bonus to how strong the Attachment is. So far, the cap is +35 to any given attribute, while more 'rare' combination range from 1-?.
The +35 point system is created with the help of looted clothing/armor/and weapons. Here's how it works.
First part:
A modded stat piece of loot (example will be a shirt) contains a +18 on Precision. This will be used with the reverse engineering tool by the Trader. When reversed, there will be a power bit that comes out. Now depending on the RE skill of the Trader, it will be raised anywhere from 18-20ish without the Precision bonus.
Part two:
Any two pieces of electronic type loot combined into the same RE Tool will create a Modifier Bit. The Modifier Bit will range with any skill that is currently involved with the game. Let's say the combination gives an Strength modifier.
Third section:
Now. The Trader will throw the Power Bit and Modifier Bit together. Then use the "Creat Skill Attachment" (somewhere along those lines), and confirm the process. Now, the Tool will create a Skill Enhancement Attachment (SEA) with the pieces we used. Out will be created the SEA of Strength +21 (example).
If you want a 3-stat Bit. The trader will need a 1st Order Power Bit, a 2nd Order Power Bit, and a 3rd Order Power Bit.
To do so..here we go.
2nd Order Power Bit:
To create these is pretty random really. A single modded loot can sometimes give a 2nd Order, however to insure you get one, you can have a modded piece of loot (again weapon/shirt/armor) with two mods such as Stealth +19 and/or Agility +18. RE those. The Bit will use the 19 since it's the highest and again depending the Trader's RE skill wil give a bonus. So, we'll use 20 this time.
Now with this Bit and another Modifier piece, we'll use Constitution for example, the Trader needs the first SEA of STR+21, the 2nd Order Bit of 20, and the new modifier of CON. Now, throw all 3 of these pieces into the RE tool and select again Creat an Skill Enhancer. Now will be the Attachment of STR +21 and CON +20.
3rd Order Power Bit:
You will need a modded loot piece of 2 (rare) or 3 stats (uncommon) that will give the 3rd Order through the RE tool. Again, they will need another combination of loot to create another Modifier. We will use Agility with the piece and +23 with 3rd Power Bit.
Now to create the 3 stat attachment. Repeat the 2nd Order Bit proccess. Throw the SEA of STR21 and CON20 into the Tool with the 23 Power Bit and Agility Modifier. RE that now the SEA will be STR21/CON20/and AGI23.