Is there no way to print selected emails from a non-conversational email series of replies and sends using Gmail alone? I am using a system to which I cannot add programs.
To print just specific parts of a conversation you will need to print each reply/send individually from the conversation.
Make sure the individual email is expanded and then click the dropdown arrow.
Then click print.
To print an entire email chain:
To the right of the subject line is a tiny print button.
If you click the printer button it will automatically bring up the print popup for whatever browser you're using.