This is simply a list of all the levels where the Achievement Pickups can be found. From the Main Menu of the game, use Scenario Select to jump to the specified levels.

Achievement for One
Find the first achievement pickup in 'Spawn'.
Located in 0.3

Gamification
Find the second achievement pickup in 'Spawn'.
Located in 0.5

Double Act
Find the first achievement pickup in 'Array'.
Located in 1.8

They Seek It Here, They Seek It There...
Find the second achievement pickup in 'Array'.
Located in 1.9

Hidden Depths
Find the first achievement pickup in 'Origin'.
Located in 2.4

Not Exactly a Tesseract
Find the second achievement pickup in 'Origin'.
Located in 2.9

A Token of Love
Find the first achievement pickup in 'Associations'.
Located in 3.4

Shared Hobby
Find the second achievement pickup in 'Associations'.
Located in 3.8

Distractions
Find the first achievement pickup in 'Purge'.
Located in 4.4

Dwindling Capacity
Find the second achievement pickup in 'Purge'.
Located in 4.8

The Last Place You Look
Find the first achievement pickup in 'Invert'.
Located in 5.1

Darwinian Collection
Find the second achievement pickup in 'Invert'.
Located in 5.4

And In the Darkness, Find Them
Find the first achievement pickup in 'Itterate'.
Located in 6.2

Achievements, All the Way Down
Find the second achievement pickup in 'Itterate'.
Located in 6.7

The Breakfast Club
Find the first achievement pickup in 'Design'.
Located in 7.1

A Selfless Act
Find the second achievement pickup in 'Design'.
Located in 7.10

49 Shades of Grey
Find the first achievement pickup in 'Generation'.
Located in 8.5

Needs More Hats
Find the second achievement pickup in 'Generation'.
Located in 8.10

That's What You Gets
Find the first achievement pickup in 'Y+1, X+1'.
Located in 9.2

The Final MacGuffin
Find the second achievement pickup in 'Y+1, X+1'.
Located in 9.10