In the first Borderlands game, players could upgrade their ammunition capacity and storage by buying upgrades from the vending machines. This time around, players will have to acquire a rare material known as Eridium and turn them in to a shopkeeper to purchase these upgrades at increasingly higher fees per upgrade.
Though the material is described as rare, it’s fairly easy to find and players should have no difficulty accumulating the necessary amount of Eridium to purchase their upgrades over a period of playing the game normally.
The easiest, and most legitimate way of acquiring Eridium without actually exploiting any in-game quest mechanics is to head on over to the slot machines in Mad Moxxi’s bar. It’ll take a bit of scratch, but winning the Eridium jackpot can net you anywhere from 20 to 40 pieces of Eridium to purchase your upgrades with.
If you lack the patience, or the money to play the slots, you can always use the following “exploit”:
1) Quick travel to Three Horns Valley.
2) Walk on over to the Bloodshot Stronghold just north of the quick travel terminal.
3) Kill a unique mob named “Bad Maw” outside the area.
4) Head into the Bloodshot Stronghold.
5) Save and quit the game.
6) Continue the game, and walk back outside and kill Bad Maw again.
7) Rinse and repeat until you have more Eridium than you can shake a cannibal midget at.
The best part of all is that it'll work on any platform you've got the game on, be it the PC, PS3, or Xbox 360.
[This article is part of a series of guides for Borderlands 2.
Find out about Mad Moxxi's Vibrating Gun.
And here's how to get additional Golden Keys and Veteran Skins.]