I should have said this tiny feed horn is to go on end of a Noosat 9000D LNB for 22 GHz water maser observing.
Eduard has very kindly given me training on how to make this (without string) - the big question is whether I am capable of getting it to work!
So far, I have a 1.2m prime focus dish which I have mounted on my Sky Watcher NEQ6 Pro mount for this purpose. So the current step is to sort out the LNB/feed horn and mount it at prime focus.
I also need to test the LNB to ensure it works with a NESDR SMARTee XTR purchased for this purpose.
Andy