[Chimera-users] Saving multiple identical PDB in a single file with unique chain ID

Hello, I'm building a tubulin lattice. I want to save the structure as a single model, however, the chain ID for each monomer should be different from the other ones. If I copy/combine my alpha-beta tubulin monomer, I get another structure with A and B chains. What I want is different chain letters. How can I do it? Regards.