How do I let a guy know that I'm attracted to him?

Before the project ends, you should casually ask him to join you for lunch, or coffee. Something that is not so heavy and that you could be matter of fact like, hey, I'm going down to get some coffee, want to join me? Once you do that when the project is going on, once the project ends, it will be easier to hang out.

When you two are together you should talk to him about other things (not just the project). That way you make it more personal.

When you are together and working on your project, after an hour or two, say you're bored and you should both take a little time out to relax. If you do that and go sit somewhere else, or clear the stuff you're working on away, make sure you have something to talk about. Like, you could talk about something that's happened in school, or if you are both a good friend of someone. You could talk about that. Or if you wanted to be bold (which is hard for us shy girls, but sometimes we just gotta be confident! ) you could both be working on the project and say you brought over a movie to watch after you've finished, or when YOU decide you should both take a break! If you put a movie on and you're sitting next to him, you could keep looking at him and just smile until he looks at you. Then just go for it and kiss him. You said that the feeling's mutual and maybe he's just to shy in case he gets rejected off you. Just gently kiss him and make it very sweet :) I hope this helped, and if you possibly want to know more, talk to me and I'll try help you as best I can :) Good luck! X