The Mass Trick is an in-game exploit involving Cargo Expansions and various outfits that grant the player more mass than the game allows for that ship by default. The trick will not work on any ship with 279 or more tons of cargo, as that ship will be able to buy the Sigma Mass Expansion, seven Mass Retools, and five Mass Expansions, as they have enough cargo space to eliminate the need for it. In addition, the trick cannot be utilised by any ship that does not have at least 15 tons of free mass with two Sigma Mass Additions, as that ship is unable to fit a Cargo Expansion. Furthermore, although extremely rare, a ship that cannot get at least 12 tons of cargo with cargo expansions is also unable to perform it. Finally, Vell-os, Krypt, Wraith, and Hyperioid ships cannot perform the trick since they cannot purchase any type of expansion or retool, though they have little use for those since they can only purchase Marine Platoons.
To perform the trick in the most optimum manner, the player first needs to completely empty their ship of all outfits that take up mass, such as weapons. Next, they need to purchase two Sigma Mass Additions to maximize total free mass, after which they need to purchase as many Cargo Expansions (NOTE: NOT Cargo Retools; these cannot be sold and therefore do not work with the trick) as possible. If the player is unable to put five Cargo Expansions on their ship, they should buy more as soon as space permits (75 tons of free mass are needed for all five). Once they have fitted as many Cargo Expansions as possible into their ship, they should attempt to purchase mass expansions and retools in the following order:
- Sigma Mass Expansion;
- Seven Mass Retools (five in Federation space, two in Polaris); and
- Five Mass Expansions.
The Sigma Mass Expansion should be bought first as it grants 100 tons of free mass for 120 tons of cargo space, the equivalent of ten Mass Retools. Retools should be bought next as they can grant up to 70 tons of free mass for 82 tons of cargo space. Expansions should be bought last because they are the least efficient; only up to 50 tons of free mass for 75 tons of cargo space. Finally, the player should sell the Cargo Expansions. This will result in a ship getting an extra 220 tons of free mass if they are able to buy all the expansions and retools. Even if they are unable to, the space gained is often significant and allows for many more outfits than otherwise possible.
The trick does have its drawbacks, however. Any ship that gets up to 279 tons of cargo space with all of the Cargo Expansions will have zero or negative cargo space. Most of the time, it goes quite a way into negative space, preventing the player from recovering cargo space when selling Mass Expansions. Accidentally selling them will force the player to sell enough outfits to repurchase the Cargo Expansions in order to repurchase the Mass Expansions. The biggest impact, however, is that the player is unable to run any mission that requires cargo space, including almost everything from the Mission BBS and all the major storyline strings. Because of this, it is strongly recommended that the player uses an "untricked" ship to play through a storyline first, lest they be forced to give up a ship they have already spent at least several million credits on to finish the story.