Rather unlikely, I believe.
The FKD is a copy of an older type of wooden Reisekamera. The holders for these (the originals) were more often than not incompatible with any other camera than the one they were made for. The Mentor is a little newer (not newer thanthe FKD, but newer than the "originals") and has a certain degree of standardisation: All Mentor holders fit all Mentor cameras - a truly great improvement!
The best (maybe only) way to get a matching holder is to measure the needed dimensions, and then pester every ebay seller into measuring theirs. I managed to get 3 holders for my 18x24 Reisekamera this way.
BTW - if you give me the dimensions, I'll measure my FKD holders.