166.099 movement holder/spacer/case ring (cal 1481)

I have a small issue. I have all the parts ready to assemble my 166.099, except for one piece: the movement holder/spacer/ring. I’ve searched extensively but unfortunately haven’t been able to find one, not even previously sold pieces. I was wondering if anyone could point me in the right direction or knows where I might be able to get one? So far all parts are genuine, and hoping this one last piece also can be.