Super blurry photo of my parts for this hinge, all cut out of 11 gauge steel with an angle grinder and a zip disc. I used Google Sketchup to make a paper template to fit the arc of the barrel circumference, and I cut the bolt brackets from the remaining scrap. Purchased the weldable steel hinges.

Using paper to mock-up the lower bolt brackets.

I was very happy to find that the hinge allowed the barrel top practically zero wiggle room as it is lifted and returned to its resting position.

Priming with Rustoleum.

I'm not super proud of the appearance of my welds, but they're plenty strong enough. Still have yet to paint the hinge, after I choose a color.