It is proving SOOOOO difficult to find a process for making Tintypes that I would actually be able to do!
I went to the library and the one book listed with the word Tintype or Ferrotype in isn't actually there any more, helpful! I did find other books on earlier processes, particularly the Daguerreotypes, made using plates of silver and put into glass frames to stop them getting scratched easily. Here is an example of one I found in a library book;
The photograph was taken in black and white with the tinting done later by hand. Whilst this process produces much nicer results than Tintypes, the process involves using mercury so there's no chance I would be able to recreate them! Not the safest pictures in the world!