For Trump rallies, homemade signs are forbidden. The only exception was the Tampa, Florida rally at the end of last month. After that rally, Trump rallies returned to the no-homemade-signs rule. Were they allowed in Tampa because July was the month the world would know the Truth and this was a good way to raise the number of Q messages in the rally's audience? I tend to think so but may be wrong. I know the Q shirts are always allowed.
Why are homemade signs forbidden? I think the signs cause visibility issues with the rally coordinators when they are raised and block cameras. I don't think it is because they are trying to keep negative signs out. If that were the case, someone could just wear a negative shirt, right?