Tanks, Reservoirs, Pontoons, can usually be repaired using a doubler patch that uses a lap joint
Usually this test is given with a procedure that allows for 1/8" electrodes.
But some welders are being required to use 5/32" 7018 which is more challenging. This video has a few tips that should help
Outside Corner joints on 11ga 6061 aluminum are enjoyable. This This Aluminum cube project is a good way to get some practice on outside corner joints.
Some Structural welders are being required to make welds like this 5F round tube to flat plate using 5/32" 7018. Here are a few tips on machine settings, arc length, and body positioning