Joining PVC pipe to galvanized sheet metal for downspout?

what's the best way to connect these two materials together for use as a roof downspout? the pvc is 4'; diameter thick wall, 90 degree bend. can't have screw threads on the inside of the opening due to leaves and twigs getting caught.Joining PVC pipe to galvanized sheet metal for downspout?
You could use a fernco rubber coupling but don't ever spend a cent in Home Depot unless you like getting ripped off. (long story) I would get a 4'; thin wall cap (it will fit into your sch 40 90 elbow) cut the shape of your downspout into it, slide the metal in and caulk the heck out of it.Joining PVC pipe to galvanized sheet metal for downspout?
I would try a Fernco rubber connector. They come in different sizes to accommodate different sizes of pipe. It's one possible solution and can be found at Home Depot.
put them together and put a couple of rivets into it

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