How do you convert a decrypted .3ds file into a non-encrypted .cia file that you could then just install to the Citra emulator?

I’ve been trying to do this, because I’m fairly sure that it will take up less space on my computer if I do. I can’t seem to figure out how to do it, though. Can anybody provide me with some tips on how?

This won’t decrease the storage space required. It just moves the file to a different folder in a different format. The amount of data does not change.