The phrase "attach blue" is correct and usable in written English.
It can be used when instructing someone to attach something that is blue, such as a document, file, or object.
Example: "Please attach blue to the email before sending it out."
Alternatives: "add the blue item" or "include the blue document".
After the death of the two doctors in the collision with the Lukoil Mercedes, a group of drivers began attaching blue sandbox buckets to the roofs of their cars, in imitation of sirens, as a protest against the abuse of the siren by the city's bankers and oil executives.
In Experiment 4, half of the circles had an attached blue circle and the other half had an attached black square to simulate two groups of agents holding different objects that could be exchanged.
Despite the warning of a sellout, Honduran fans attached blue-and-white banners to their cars and beeped their horns all the way from New England, from the Carolinas, from New York.
Here, slide the white corner into the blue pocket to attach the blue piece.
Cultural observers here lamented that the exploitation of political authority reached an apogee when it came to driving, including the right for ministers to attach flashing blue lights to their chauffeur-driven luxury sedans so they can speed through Prague traffic with the urgency of ambulances or police cars.
Attach a blue jewel on the center of the chest.
Attach the blue and red rods to the the black connector in a circular motion.
Since 1867 London has paid tribute to distinguished citizens and visitors by attaching circular blue plaques to their places of residence.
Arsenal are "keeping tabs on" Mikel Arteta, the technical term for shooting him with a poison dart from a jeep and then attaching a blue ringpull to his ankle.
The creatures are around six centimetres wide and clear, but they are attached to blue floats that look like shells, which sit flat and allow the sailor-jellies to travel across the water.
