Expanding Copper Pipe?

[Tenson]

I had a go with some copper pipe. It does work and will form to the shape without splitting, no need for heating. Copper pipe for plumbing comes in 'half hard' or 'full hard' spec and the 'half hard' stuff is suitable for bending and flaring. - https://www.youtube.com/watch?v=3e103_ULgpI

However... it took a LOT more pressure than I expected. I pressed a mandrel into the 28mm pipe using a bearing puller and even that found it tough. I had hoped to rig up a big lever to press it, but no way would it be strong enough. Okay I could build a machine to do it, but I'd probably spend longer making the machine than simply getting on with the plastic ones. So I'll go with plastic.