So if you can't get your parts on your timeline, you will sue the guy to make sure none of the rest of us will ever get any in the future?!? This guy is an enthusiast who makes these parts as he has time, not some big faceless corporation. If you ordered COD you aren't out anything, and if you have prepaid you will just get your money back.
Actually, if I can't get the parts that I have paid for 3 months after I was promised them and have had numerous empty promises from the seller, that's right: It is time to get the right people involved.