How to design a 40cm billboard

First of all, what is the border you are referring to? If it refers to a 30cm side pattern, and your billboard has built-in lights, then I suggest you cancel this plan, because it is normal for 10M inkjet printing to be 20-30cm more or less; of course, if it is a peripheral The lighting is better, because this problem can be solved through puzzle
For a 6mX10m billboard, the general method is to create a cmyk pattern file with a size of 640X1040cm and a resolution of 20, and then set the reference line. Leave 40cm around. This 40cm is the bleeding area. You can't put key content inside, and the rest can be done as it should.
As for the 30cm border you mentioned, if it is a pattern, if it is a color block, then It must be 50cm in size; if it is striped or something, it must sit outside the bleeding position of 40cm, or even more