How much does it cost to make a big led display?

It depends on what you do. There are indoor and outdoor ones. Monochrome, bicolor or panchromatic. Full of color, accurate.

There should be detailed instructions, and the size of the display screen should be calculated in square meters.

For example: outdoor full-color P 10 series in-line display screen, the all-inclusive price of the project is about 4K per square meter (Remington Optoelectronic Technology).