They found the plans for this in their archive. It had just been forgotten about. People are always finding forgotten treasures in the back rooms of archives, b

They found the plans for this in their archive. It had just been forgotten about. People are always finding forgotten treasures in the back rooms of archives, because they're full of ancient stuff and actually getting the right pair of eyeballs to recognize the importance of old stuff is really hard. Digitizing everything helps, but the enemy is still volume, time, and money, and digitizing costs even more money.