Quote Originally Posted by Fotografi Godsbanen View Post
The three light mixing boxes and register plates would be those for 4 x 5 inch film, 35 mm films and 6 x 7 cm or 6x9 cm films.
By "register plates", I assume you mean the masks that fit in the carrier such as: http://www.durst-pro-usa.com/FEMOMASK.php

As Neil has already pointed out, Femomasks are increasingly difficult to find, but do pop up from time to time on ebay. Your other alternative is to use a pair of glass inserts from someone like Focal Point Glass.