This block ist designed to explain the principle of 3D scanning. The Block is exactly 80 mm long in x-axis-dimension and 40 mm in other dimensions. If you look 2D to the origin of the coordinate system like a webcam the block seems to be 90 mm long. With a laser line held under an angle of 45° there is an offset in the line. When the angle is known, the height of the block can be calculated with tan x. If the angle is 45° the tan 45° is 1. This means that the horizontal offset of the laser line ist exactly the same as the height (z-axis coordinate) of the point.
If the webcam makes a video while the laserline is moved, you can scan the whole block and give not only width and length but also height of each point on the roof of the block by measuring the horizontal offset.

To visualize the 3 axes the block has inbuilt coordinate axes.