Expanding Copper Pipe?

[Tenson]

I need to make some bass ports for a small speaker - 400 of them!

I was going to use PVC pipe which is easy to form when heated in an oil bath. However It takes a lot of time.

Each speaker has 2x 20mm OD ports and if I could get 28mm OD pipe (1mm wall thickness) I would only need one per speaker. PVC pipe seems to go up from 25mm to 32mm, so no help. However copper pipe is 28mm with 1mm wall.

Do you think I would be able to form it in the shape shown? How? I've seen a metal ram used for more basic expansion. I am thinking the end flare might be too extreme and crack the pipe. The edge of the lip needs to end up at 90 degrees to the pipe length. Any tips?