BioShock

Actually this was the last achievement i needed in this game. so after walking through this whole game and collecting nearly everything that came along my way, i still hadn't enough "stuff" to invent "other stuff".
so some help:

-dont use U-Invent untill you get the "Clever Inventor"-Tonic. This one will reduce every requiered component by 1. It can be found in Olympus Heights in Dr Suchongs Apartment.

-as soon as you have it, equip "Scrounger"-Tonic (after reasearching Leadhead Splicer level 2), you will now have the chance to "re-search" everything by hitting LT, most of the times you get more / better / more useful items after reseaching.

-the things you should ESPECIALLY take a look for: Battery, Kerosene, Shell Casing.

EDIT: if you go for this achievement towards the end of the game, take a look in the comments for a great tipp by Axel GERMANY

AxelGERMANY's guide:

If you go for the achievement near the end of the game (it has to be done before the final boss fight) you might have problems finding enough enemies with the required materials.

Therefore I suggest visiting Arcadia -> Farmer's Market -> Silverwing Apiary where the bees are located. Activate the smoke in order to prevent the bees from attacking you and search the hives. Everytime you press "A" on a hive a Splicer will spawn. Kill all of them until the smoke disappears and collect their materials. Repeat until you have enough materials to create 100 items at an U-Invent-Station.

Make sure you have these Gene Tonics equipped:

- Clever Inventor (will reduce the number of all components required to invent an item by 1, down to a minimum of 1. )
[Received at research level four for Thuggish Splicers. ]

- 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.)
[Acquired from the second-to-last gift given by the Little Sisters for rescuing them.]

Note: Prolific Inventor (doubles the quantity of an item produced using the same number of components) won't help you unlock this achievement since it requires you to "perform" 100 inventions instead of creating 100 items (the achievement description is slightly wrong).

Good Luck!
all credit goes to Axel GERMANY it worked for me so i though i would post it on the main page. thanks to Axel GERMANY

Some tip for those going for this achievement;

Try to avoid inventing until you get the Clever Inventor tonic in Olympus Heights, it reduces the amount of materials you need for each item. The Tonic is in Dr Suchong's apartment near the first sample of the Mind Control Antidote, you can't miss it. Until you get this tonic try to only invent items as you need them.

The Scrounger Tonic (unlocked after researching Leadhead Splicers to Level 2) allows you to re-search objects and containers by hitting LT on the loot display.

The unlock for Rosies at Research Level 4 causes them to almost always drop invention parts. If you start researching them when you get the camera you should be able to get their research to level 4 by the time you get to the Farmer's Market. Don't forget to loot their rivet guns.

Turrets sometimes drop inventing materials. If you've been hacking them through the game double-back and destroy them.

This could just be for me but the Spider Splicers seemed to have a high drop-rate for invention items, especially items like Bee Enzyme and Shell Casings. Fort Frolic is the best place to find them.

As others have commented, the Prolific Inventor Tonic has no effect on this achievement.

I recommend doing it after completing the Proving Grounds but before you take the elevator up to the final boss battle. Save here then drop every possible invent item in the nearby U-Invent. If you haven't gotten the achievement don't worry; you're still free to back-track through the rest of Rapture.

Just like SneezeSomeMilk this was the last achievement I needed. This is how I obtained it.

I first deleted all BioShock information off my hard drive. I don't think it's necessary but I wanted to be sure it wouldn't glitch on me.

Started up a New game on Easy. I didn't started receiving loot like batteries, tubes ect until about an hour into the game.

When you start getting items do not build anything until you've got clever inventor (found in Dr Suchongs Apartment in Olympus Heights), and scrounger tonic (which is obtained by researching the thug splicer to level 2). Once you get the camera every splicer you see take the picture until level 2.

Axel GERMANY added a brilliant spot to farm supplies. When you must collect from the bee hives, every-time you open a hive a splicer will spawn dropping items. max on items is 50.

Once I had enough I played through the game normally until I got clever inventor.

Hack the nearest U-Invent and build the most supplies for the least material. After this I didn't have enough so I continued through the game and I eventually got it during the objective secure second dose of lot 192.