Modding Borderlands is fairly simple, and is fun and easy to do with a few basic tools and skills.
First and foremost, modding Borderlands or any game is being able to transfer the game save file to a computer program in order to alter or fix any negative bugs or glitches that game developers were unable to correct or missed within the parameters of the game/program or just to make better since modders creativity is not restricted by deadlines and incorrigible co-workers. It also allows players to create their own personalized experience, and to help make things new again. As of late there is a negative stigma around modding since modders have been known mostly for cheating, but just like anything in life there is a responsibility for modders to use it for good, and not evil, so go out there, and make the game better, and more exciting instead!
Some of the things that will help you with modding your game file are listed below:
Ways to Transfer Data (360 only):
Microsofts Data Transfer Kit- Around $15
Datel XSATA- Around $50
Datel XPORT- Around $50
you may also use a USB stick/Flash Drive now, some programs you could use are, USB XTAF Explorer or, Modio. The USB device must be at least 1GB in size or you cant use it also, you can only use up to 16GB of space.
Game Save Editors:
WillowTree on SourceForge - 360, PS3, and PC (Recommended)
Gibbed's Save Game Editor - PC and PS3 (Good for Patch 1.21 and below)
HxD - Hex Editor
There are also a bunch of other Standalone Borderlands Save Editors going around
Basic Guide Lines for Modding:
If you choose to ignore the following guidelines it is very likely your mods will not appear in game.
This is as a result of patch 1.30 of which removes overpowered weapons or weapons that allowed players to have a creative outlet.
1. Use the same Manufacturer throughout your weapon or item. No mismatching unless you're modding scorpios, then experiment and post.
2. Don't use parts from DLC's unless you bought that specific DLC. For instance, no parts from Mad Moxxi's if you don't have Mad Moxxi's DLC.
3. Use the correct parts outlined in WT. So don't go using sights for barrels or mags for stocks it will not work anymore unless you're on PC, then NVM and do what you want.
If you wish to get more powerful weapons I suggest experimenting with stock parts.
Borderlands Weapon Editor v2 - Helps build weapons from scratch. Created by Synthpixel. Dead Link
Gear Calculator - Build weapons from scratch and have a variety of weapon stats calculated for you. All Knoxx guns are now supported. Export to Willowtree also supported.
Willow Shrubbery - Online save file viewer/browser. View gear from either your own saves or other people's saves. Also interfaces directly with the Gear Calculator.
Rehasher & Resigner:
Through some personal testing with WT or Gibbed Save Game Editor for Borderlands (use for older patches), you do NOT necessarily have to use the correct parts on the correct weapons.
Example: I've used rocket launcher, pistol, smg, and shotgun parts on a sniper rifle.
The weapons viewed in-game physically may appear to have missing parts, but they usually function correctly.
Also: you don't even have to use magazine parts in the mag slot, or scope parts in the scope slots.
Mix and match, and see what you can come up with, some bizarre and boredom annihilating weapons are possible before patch 1.30. Therefore if you delete the game save data that stores the latest update from GBX, you can continue to have as much fun as you can stomach. Plus, fan created weapons through the UDK are posted on GBX forums, so have fun be creative, and share with fellow gamers!