Normal film plate holder part 2

In oktober 2010 i posted some pictures how to modify a normal film holder to a wet plate holder.
Here's the post http://collodion-art.blogspot.com/2010/10/normal-film-holder-for-wet-plate.html
I have got several questions how i manage to hold the plate into the plate holder as it has no door with a spring.
Well, actually this is quite simple. Just take a normal plastic (limonade) bottle. Cut a small part out of the bottom part (which is mostly the stiffest part) of the bottle  (about 1.5 x 3 inches) et voila:  you have made yourself a spring for your plate holder.
Just as simple as that.
Try to make it of a white bottle which makes it much easier to locate when you are working in the dark room.