NOTE: Some Blueprints appear twice during the duration of the campaign. But, they can only be discovered once. Once found, they will not appear a second time.
High Overseer Campbell
Bonded Galvani Weave
Effect: Improved Armor
Location: Located inside the workshop, in the backyard behind the Overseer’s mansion. The blueprint is locked inside a safe, the key is on a nearby workbench inside a bottle. Pick up the bottle and smash it to get the key inside. [Thanks to SuperNofa for the extra info.]
Lens Magnification
Effect: Improved Lens Magnification
Location: Located inside Griff’s Pawnshop, you’ll first need to rescue Griff from the building to the right of the first Wall of Light in Mission 2. Save him from the thugs, and you can buy blueprints from him.
Sokolov’s Formula
Effect: Piero can create Health Elixir
Location: Located inside Griff’s Pawnshop, you’ll first need to rescue Griff from the building to the right of the first Wall of Light in Mission 2. Save him from the thugs, and you can buy blueprints from him.
House of Pleasure
Incandescent Paste
Effect: Fire Bolts
Locations: Return to the Distillery, and use the valve-controlled door to reach the hidden blueprint.
Lens Magnification
Effect: Improved Lens Magnification
Location: Located inside Griff’s Pawnshop, you’ll first need to rescue Griff from the building to the right of the first Wall of Light in Mission 2. Save him from the thugs, and you can buy blueprints from him.
The Royal Physician
Sokolov’s Formula
Effect: Piero can create Health Elixir
Location: Look inside the Greenhouse of Sokolov’s mansion, accessible from Sokolov’s workshop through the library.
Folded Galvani Resin
Effect: Upgraded Boot Stealth
Locations: Early in the mission, look inside a warehouse on the left side of the canal, in the first bridge area.
Lady Boyle’s Last Party
Spiked Grenade Housing
Effect: Sticky Grenade
Locations: Before entering Boyle’s mansion, look around for a guard station at the gate near the entrance. Inside, you can find a blueprint on the guard’s desk.
Return to the Tower
Small-Scale Combustion Refinement
Effect: Explosive Bullets
Locations: Search the General’s office in the Dunwall Tower interior area. His is one of the four central offices up the stairs.
The Flooded District
Spiked Grenade Housing
Effect: Sticky Grenade
Locations: Look inside the building filled with armed criminals, and search the wrecked hallway for this blueprint.
Incandescent Paste
Effect: Fire Bolts
Locations: Search the lower level cellar near the tunnel’s exit.
Bonded Galvani Weave
Effect: Improved Armor
Location: Search the chests in Daud’s Office, you’ll need Daud’s key to reach this chest.
Small-Scale Combustion Refinement
Effect: Explosive Bullets
Locations: Enter the Central Rail Station, look inside a crashed train car to find this hidden blueprint.
Folded Galvani Resin
Effect: Upgraded Boot Stealth
Locations: Search Daud’s office for an unlocked chest to get this blueprint.