There's No Way InEdit
The path to this cube is blocked off after one of those puzzles has been solved : "Leap of Faith", "Logic 101" or "A jump too far" ; solving one of those puzzles triggers a transformation of the "There's No Way In" room and it becomes impossible to access the pink cube secret room, so it must be accessed at the very beginning of the game. So, at one end of "There's No Way In" in its initial version, there is a set of green-colored stairs with a yellow and black border. Walking down these stairs and then back up them will bring you to a room with two pyramids, one cyan and one magenta. Looking at the cyan pyramid will reveal the pink cube. It will follow a path down the cyan pyramid, across the floor (not visible, but it is audible), and up the magenta pyramid.
Three Paths in SightEdit
One of these can be found in the gallery located at "Three paths in sight", its path borders the room starting at the left and going around clockwise till it on the right, then disappears. There is a second pink cube in the gallery as well, but it is bugged and unobtainable. There is, however, a clipping glitch that can be used to obtain it.
Window of OpportunityEdit
Another can be found at the "Window of Opportunity", go to blue, then walk so you can see red, but don't trigger the switch, now the other side is green. repeat this again and now it will be pink, it is in the shape of the number two.
Down the Rabbit HoleEdit
This one can be tricky go into the "Rabbit hole" and chain your jumps such that it gets lower and lower, there are multiple ways to make this happen. you can either jump such that it never comes back up. OR you can let it come all the way up and fly in the air and come back down, this takes less cycles but each jump is more important. either way, get to bottom of the shaft, past the null field. walk off and at the bottom there is a path with a pink cube infront of you.
Cry Me A RiverEdit
Inside the fake wall, use cubes to pillar upward and at the top is a pink cube.
Manage to get up the fake stairs after opening the door to the left on this room for another '2' shaped pink cube.
A Wall Without StairsEdit
After getting up the wall, crossing the appearing platform, and getting to the bottom of the jump pad, there is a green wall at the back of the jump pad shaft that is made of green cubes. There is a pink cube behind this wall.
Link in a Chain ReactionEdit
Between the window to the yellow gun platform and the sign there is a wall that you can walk through.
Four Different ExitsEdit
In the room just above above the ground-level entrance, there's another pink cube.
Taking Baby StepsEdit
A stairway materializes as you walk forward; Jump here to fall through and walk forward through the wall to find another pink cube.
The Butterfly EffectEdit
Underneath the jump pad used to get to The Butterfly Effect is a fake floor leading to a pink cube.
Stand on pink ring, while looking at it, add blocks under yourself, lifting yourself up, there will be a pink block with 2 shaped path.
This pink cube is unobtainable right now without console commands. It is located underneath the black circle on the ground between "WTF?" and "HMM..."
Enter the chase. When you see the Black Ghost float upwards, turn back and down the green staircase. There is now a door there. Behind it is the pink cube.