I would not recommend flux core wire for sheet metal work. The machine I have (A Lincoln Handy-Mig - paid about $350 for it) specifies different polarities for MIG and flux core welding, and the setup for flux core increases penetration, which tends to blow holes in sheet metal. Also, you have the flux to clean off after you're done welding.

If your going to get a dual setup (MIG/Flux core) wire feed, bite the bullet and get a bottle of C02 (cheaper than argon, and works reasonably well). You'll be happy you did. Save the flux core wire for thicker stuff you'll eventually wind up welding.

Kevin
1951 Chevy 3100 work truck
Follow this saga in Project Journal
Photos
1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car)
Busting rust since the mid-60's
If you're smart enough to take it apart, you darn well better be smart enough to put it back together.