I'm supposed to be done with my contract by the end of August, but this opportunity has been incredible for me and I don't mind working for him without getting paid since there are so many opportunities in the place I work.
I'm working as a software engineer and I am also doing research, which at the end will result in me having my name published in a paper. I would like to continue my scientific journey with this research facility because I think it's a great environment to learn. I'm not looking to get re-hired and make the same amount/more money than I am now. I won't be working full-time if I want to work for free because I also have my PhD program. I would like to get a great recommendation for future jobs I'm applying for and I would like to have more opportunities to participate in research that will get me published in more papers.
How can I ask him this?
Trivial: I'm a girl, since everyone is assuming I'm not.
Edit:
The question is: How can I ask my boss if I can stay on a project for free, after my contract is up?
My question is not: Should I work for free or not? or: Is it legal for me to work for free?