I just used up my last stock of 1.6mm thick annealed 1200 aluminum on
some spinning and went to re-order.

Guess what?

You can no longer buy anything but 5000 or 3000 grade aluminum sheet
in New Zealand!

I checked with all the limited number of aluminum suppliers here and
*nobody* can supply.

Talking with a couple of professional metal-spinners, they confirmed
the situation.

What a pain in the backside that is!

Neither 5000 series nor 3000 series sheet will spin (even when
regularly annealed) to anywhere near the degree that 1000 series does
so I'm stuck with looking at other options for making a new batch of
venturis. It's either cut and weld (which produces sharp contours and
is very time-consuming) or turn from solid which is also slow and
expensive.

What is the world coming to?