I completed my water trough. This should make things less messy and less smoky.
I made it out of AluPanel. I thought it would be a simple way to get a water tight and corrosion resistant part.
I cut out the basic shape with a 3 inch perimeter around it. I then hand routed a V groove down to the far side metal using a 45deg bit. I thought about doing some fancy overlapping corners, but the placement of the V grooves would be very critical and I did not know the bend allowances. I ended up just cutting out the 4 corners. They were already V grooved, so they fit together really well.
I takes quite a bit of muscle to fold the longer edges, but it worked pretty well. A wider angle bit like 60deg will might have made it easier.
I then used clear RTV to seal the corners. I also ran a bead along the inside of the folded corners. The skin is pretty thin there. I did not want a little ding to cause a leak.