You can see which blueprints you have by loading up chapter 6. Instead of going into the relaxation room, take a left turn from the start, and they'll be on the corkboard on the wall to your right.
There's Blueprints in every chapter except chapters 5 and 9.1st Chapter - 1 Blueprint:**EDIT** USE THE EMERGENCY EXIT SIGN, IT'S MUCH EASIER THAN THE CHEESE!
Right at the end, where you need to use the slice of the cheese wheel to knock the panel walls down. Carry this through until you see the sky-patterned wall in the 'exit' door. Just before that is a pit that you'll fall down. You want to make the cheese slice large enough to make a ramp that you can jump over to the other side.
If the cheese falls down the pit, go back to the panel room and you'll see the cheese will have respawned. If you fall down the pit, quickly as you're falling, pause and restart checkpoint.
Once you're across the pit, go behind the sky wall and you'll see the blueprint. Interact with it with B, and then fall down the pit to save it by finishing the chapter. 2nd Chapter - 2 Blueprints:
The first blueprint is in the room where you need to use the exit signs to escape out of the red and white square room. As soon as you enter the room, you'll see an exit sign on the floor to your right. Pick it up, make it bigger, then use it as a ramp to go over the top of the wall you're looking at (if you'd turned right from the entrance). On the wall of the room 'border' that you were just in, you'll see the blueprint. It's lit up slightly by light so if you can't find it, just go around the edge of the room, examining the backs of the walls you just escaped from, and you'll find it.
The second blueprint is in the room with the moon and the skylight. Use the cube and the cheese slice from the moon (you have to pick up the moon through the skylight and make it bigger to pick up the items) to make a ramp up through the skylight. If it helps, I used the cheese to ramp onto the cube, then when on top of the cube, I used the cheese to ramp up to the skylight and jump out. Up here, the blueprint is on the floor near a stepladder and a couple of traffic cones. 3rd Chapter - 2 Blueprints:
The first blueprint of this chapter is in the yellow room with the dice that move up/down and left/right in columns of chipboard. You want to raise the dice up enough so that you can jump on top of it from the horizontal-moving dice. Then look to the wall. You'll see a blue vent. Pull that out as far as you can. If you jump up in place, you can see a blueprint laying flat on top of it. Jump across from the top of the dice you're standing on, and try and trigger the blueprint with
as you jump. This is awkward, but you can easily jump back up and try agian if you miss.
Alternately, you can get the yellow rubber duck from the dripping water-catching white bucket in the next room, and bring it back to give you a boost up to the blueprint.
The second blueprint of this chapter starts when you put down the dice that breaks and turns into 27 small cubes. Take one of those cubes with you as you progress through the next room. You'll open a die that has a drop in it. Drop in it with the small cube from the previous die. When you land, you'll be in a red room with a ledge in front of you. Use the die you brought with you to go up that ledge. The blueprint is on the left, next to a fire extinguisher. Chapter 4 - 1 Blueprint:
When you turn on the generator, you'll notice a diagonal plank of wood each side of it, holding up the chipboard 'doorway' in front of the generator, which goes through to an area with lots of shelving. Go up the left diagonal board (if you're looking at the generator with the shelving room behind it), and then jump around the edge of the chipboard doorway wall to land on the shelving units. Go along the row of shelving units and you'll see the blueprint on your left. Chapter 5 - 0 BlueprintsChapter 6 - 3 Blueprints:
The first blueprint of this chapter is when you go through your first window of this level, there will be a doorway you will need to go through, but don't go through it yet. In this room, at the back left, the blueprint lays flat on top of a cardboard box. This is the same room as a chess piece.
The second blueprint uses the bouncy castle item. When you see it, grab it, and turn around. You want to put it in front of the doorway you came through from the gold hallway, and the blueprint is behind a light on the ledge.
The third blueprint is soon after, you'll be able to manipulate your size with two magic doorways. Put one of the doorways into the giant keyhole in the wall. And walkthrough the first door. move to the edge of the keyhole, and grab the second door. Position the second door in the huge room on the other side of the keyhole. Use both doors to make yourself huge. The blueprint is on top of the blue cube-shape clock, opposite the 'room' where you just came out of, on the other side of the chess board. Chapter 7 - 3 Blueprints:
In the room with the multi-level pool with a rubber duck floating in the middle, you'll be able to move a large white die. Tilt the die so you can reach the scaffolding on the right side of the room, and you'll see a blueprint on the top.
When you fall down into a yellow room with a large dice, turn around and you'll see a yellow hallway. At the end of this hallway is a blueprint.
When you get into the infinite parking lot, a wooden room will spawn. Clamber up onto the roof from the outside, and you'll find the final blueprint of this chapter.Chapter 8 - 3 Blueprints:
When you reach the whitespace with the room labeled 'Deception', don't go inside. Instead, move around the right side, jump onto the green box, and then jump up onto the roof for the blueprint.
When you're in the filing cabinet room (by the way, this room has the last fire extinguishers and fire alarms of the game), you'll leave through a black doorway in the shadow of a filing cabinet. You'll follow some exit signs in complete darkness and then come out to a white hallway. Move behind the windows to either side of you, and behind the door you just entered through. The second blueprint of his chapter is here.
Finally, when you arrive at the white rocks/watercooler room, the moment you enter, turn around, and go around the rocks behind you to find the final blueprint behind the door. Thanks to Kyle Thee Scott for these three!