Galvanized can also get some bad things in the syrup. Use aluminum (or SS) Also, use new aluminum, not repurposed. I made 2 hoods in the past using aluminum roof flashing, then I made one using sheet aluminum in the lightest gauge I could get.
Do you still have your grandpa's brake? If yes, you are in good shape. If not, rent or borrow an aluminum trim break.
I just bend the aluminum to shape, with an overlap at all seams, then I pop riveted it using aluminum rivets. For the bottom gutter, I bought some aluminum channel, 1 x 1 x 1 and mitered the corners then aluminum welded it using a torch and aluminum rod (available at TSC and others). If I were doing it again I'd get 1.5 x 1.5 x 1.5 aluminum channel. Design a door in each side of the hood, I made mine sliders.
Dave Klish, I recently ordered a 2x6 wood fired evaporator from A&A Sheet Metal which I will be converting to oil fired
Now have solar, 2x6 finish pan, 5 bank 7x7 filter press, large water jacketed bottler, and tankless water heater.
Recently bought another Gingerich RO, this one was a 125, but a second membrane was added thus is a 250, like I had.
After running a 2x3, a 2x6, 3x8 tapping from 79 taps up to 1320 all woodfired, now I'm going to a 2x6 oil fired and a 200-425 taps.