FFR Supplied Spacers?

I've got a question about the spacers FFR supplies, for example the coilover spacers. What type of piping are these made out of? I'm trying to match it, so I can fabricate some on my own. I measured an OD of 0.75" and an ID of 0.5", but have not been able to find a matching pipe.

Anyone else have any luck with this?

Brendan