Film holders for antique cameras

[Steven Tribe]

I am sorry to say that E**y is your best bet!
I have seen FKD - both 13x18 and 18x24 - on both German and Ukraine (be careful with a few of these) listings.
I can confirm from personal experience what Ole said in July. Makers of German 13x18 and 18x24 cameras made their own individual styled plate holders.
It is likely that FKD holders will have either sheaths for film mounted or were made for film originally. Their production period carried on long after WWII.

[Steven Tribe]

As a follow up to my last post, I would like to point out listing 320815750119. This shows a new 13x18 film holder for FKD. I would NOT recommend at this price, though! There are quite a lot of sellers who are completely out of touch with what people will actually pay!
The style is quite similar to the majority of later German 13x18 with overlaping catches in front and an indent at the back. There are quite a range of both 13x18 and 18x24 FKD backs at the moment. None of them (even the NOS one) appear to have film sheaths fitted!