A Zweiverschluss is the Ihagee I meant this item fits. I found it takes a lot of the of the Zeiss/Welta holders of the day. I was wondering where all the Zws had gone as I couldn't find any useful information about them after I bought mine a year ago and while it may be relatively rare, I'm sure Ihagee sold more than a handful of them back when.
A very nice camera though, and it's become my favourite old German. Does yours have a 44mm screw for lens fitting?