I have never built a big round metal sign before. My most epic build to date. I built it out 16 gauge sheet metal. I plasma cut the pattern from a CNC cut template, welded it up, rusted it using muriatic acid and hydrogen peroxide, then clear coated it with polyurethane. I also used a really cool nutsert tool to attach the back of the sign. I think it turned out great. Here are some links to some of the products and tools I used.
CNC (CNCRP 4896) - http://www.cncrouterparts.com (Give Cory a call and tell him I sent you!)
Nutsert tool - http://www.amazon.com/dp/B003TODXQW/t...
Plasma Cutter - Miller 625 http://www.amazon.com/dp/B007FHSXOQ/t...
Mig Welder - Miller 211 http://www.amazon.com/dp/B013HGPNDM/t...
Tig Welder - Miller Diversion 180 http://www.amazon.com/dp/B00F5NVGJ6/t...
Check out my website at www.redneckdiy.com