making an ali flexible coupler

I am building a tiny CNC rotary table for my Proxxon milling machine
and now have a small 60:1 wormwheel gearbox and a Nema11 stepper to
turn it. What I now require is a flexible coupler to link the two.
I could just use some flexible tubing and I could just buy one but I
thought it might be nice to try and make one.

I have one very small aliminium coupler I got off a DC motor some
time ago. It has 6 slots cut into it, 3 in one direction and 3 in an
orthogonal direction through the adapter. This allows it to flex in
both directions easily. I think I can make these easily, I have nice
thin diamond wheels and could program the mill to take nice gentle
cuts at the correct heights and orientations.

I have some larger couplers though that have two spiral cuts through
the aluminium of the adapter so it is more like a spring in those
sections. I have been reading about thread milling on the board
recently but is that possible if the blank was held on the bed at the
correct angle?

Graham