What device, used by both a 9th century arab scientist and a 15th century italian painter, made it easier to copy three dimensional views onto a flat plane?

The camera obscura.

Explanation:

The camera obscura was first invented by the Arab scientist Ibn al-Haytham. This was the first approximation to what we know today as a digital camera.

The camera obscura was a black small box (or a room) with a small hole in one side, that allows light to get through, this projects the image in the outside to one of the walls of the box; hence, a 2D projection of a 3D object.

Around 700 years later, the Italian painter Leonardo Da Vinci also used this device to work on his arts and invested a lot of time into improving its design.

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