NCGAPilot,
Before I started work on my RV-4, I certainly shared your concerns about building an airplane. Like you, I had NO prior sheet-metal experience, NO experience working on real airplanes, and wasn't sure how big this project was going to be. I spent about a year studying the Van's brochure, and trying to add up how much TIME and MONEY this endeavor was gonna set me back. I did have some experience building a couple of RC planes, and grew up on a farm where my father taught me MANY great things about hand tools (mostly while we fixed the well-pump or some other thing that broke in the middle of the night <grin>) But I still wasn't sure if I could tackle a project this big.
I finally decided that I'll NEVER finish it if I don't start it. And I was willing to risk the cost of the tools and Emp. kit just to see if I had the skills to do this. My dream of owning my own plane, that I built myself, was at least worth that much risk.
That was about 10 years ago (just before the RV-8 became available) and I'm still working on that RV-4, but the Empennage, Wings, and most of the Fuselage are now complete, I have a powerplant and most of the instruments! I feel a great sense of accomplishment every time I look at what I've completed so far, and only wish I had started sooner.
I would say that having prior experience isn't nearly as important as having a willingness to learn, humility to admit when you don't know something (and therefore ask that so-called "dumb question"), and finally having the determination to see your dream come to fruition, no matter how long it takes.
Whatever you do, make an informed decision. (You're already on the right track with these forums) Find a nearby EAA chapter and talk to some other builders, ask to look at their projects, go to an EAA fly-in or pancake breakfast and study the finished planes up close. If you're still not sure, I read a great book a few years ago called 'Kitplane Construction' by Ron Wanttaja. I think it's in it's 3rd edition now. In it, he talks honestly about the dreams vs. the realities and many of the details of building your own plane. (Ref:
http://www.wanttaja.com)
I really enjoy the building process and find it to be one of the most rewarding experiences I've ever had (right up there with my first private pilot solo). I say go for it, you'll never know until you try.
Best Regards,