First, I would look for sponsors that are interested or have a vested interested in the project he has planned. For example, if he is building bat houses to help with mosquito control, your local public works might help. Also, you might speak with businesses for donation of any supplies that he needs.
As far as fund raisers, here are a few ideas:
Ask for items for a rummage sale. Friends and family probably have some things around their house that they could donate to the cause.
Bake muffins and look for large offices that buy pastries for staff meetings, etc. He could make cookies, cupcakes, or some other pastry as well.
Some pizza restaurants (I'm pretty sure Dominoes does this) have fundraising programs.
Detailing cars - inside and out. He could set a price list of the services, or he could put together ronze, silver and gold packages, consisting of the tasks he will do.
Let me know if you need more ideas and I'll see what I can come up with.
Congrats to your son and congrats to you GAO raising a responsible young man.
Donít tell the Lord how big the problem is, tell the problem how big the Lord is.