U-Invent stations allow Jack to craft new items from the odds and ends he finds throughout Rapture. Despite the name, Jack doesn't actually "invent" anything, instead, the U-Invent functions in a similar fashion to a vending machine: The machine presents a list of items which can be crafted and the components needed to craft each item. When highlighting an item, it shows how many of the required components the player has left. If the player has enough components to craft the highlighted item, they will be permitted to do so.
Starting with Arcadia, the player begins finding various new items when looting and searching, as well as finding the first U-Invent machine for using these items. Popular items include Automatic Hack Tools and Heat-Seeking RPGs. Some new Gene Tonics may also be crafted. As the game progresses, more items become available. Most of the items from a U-invent are either extraordinarily rare or not present anywhere else in the game world.
- Brass Tube
- Chlorophyll Solution
- Distilled Water
- Empty Hypo
- Enzyme Sample
- Rubber Hose
- Shell Casing
Some components are more easily found than others, and that may vary in each playing of the game. For example, Electric Gel is an extremely powerful chemical agent for taking down Big Daddies. There's just a little of it around, so the vast majority must be crafted. In this case, know what components it requires and make subsequent choices accordingly:
- If several items require the same components and the component is limited, the player must choose which item they need most and do without the others.
- While searching for loot, when offered items the player already has a lot of or that they know they don't need (such as an Empty Hypo after creating all the inventable Tonics), use the Scrounger Tonic to try for something else.
- Sometimes it is good to know how much of something the player has so one doesn't end up wasting components by making more ammunition than they can carry. Still, the amount of extra crafted ammunition will not be lost, as any ammunition the player cannot carry will be dropped in front of the machine.
- Like any other vending machine, it is always beneficial to hack a U-Invent; this will reduce the component costs. Using the Clever Inventor tonic provides the same effect, and the two can stack.
- Researching Rosies to level 4 will greatly reduce the amount of searching needed as its loot yield 2 slots of components (varying between 2 and 7 units per component), in addition to money and the Rivet Gun, which may also contain components.
- 50 is the maximum quantity for every component.
- NOTE: Hacking the U-Invent machine or using Clever Inventor will reduce the requirement of each component by one, down to a minimum of one. Both can be stacked.
- Scrounger will enable the player to search a corpse again for new loot. In addition to giving the player a chance to find more valuable loot, this also will help them find the right components when trying to invent a particular item.
- Clever Inventor will reduce the number of all components required to invent an item by 1, down to a minimum of 1.
- Prolific Inventor will double the quantity of an item produced using the same number of components. This is arguably the most valuable Tonic for any inventor, as this will literally halve the number of components required to produce the same quantity of any item.
- Any and all gene tonics associated with Hacking can be of notable use, as hacking a U-Invent machine allows the player to reduce the crafting cost of all items available from the machine by 1 component, which helps save on raw materials as well as making the crafted items more readily available by making them cheaper to acquire.