I have a couple of right angle corners which I acquired when setting up my darkroom. They are made by Paterson and are plastic with magnetic bottoms. I assume they are meant for borderless printing and really I'd need four(one for each corner. While they may hold each corner, they don't appear to be able to hold the paper flat as they can't hold the paper down without creating a white silhouette of the corner and as such merely form guides into which the paper is placed.
Each corner has a rounded raised part at the 90 degree corner as if the paper was meant to lie inside the corner rather than on the easel but this would raise the paper off the metal easel at the corners and presumably it would sink in the middle.
Maybe the raised parts are simply the result of the way the corners are made in the mold and have no function and I am looking for more than is there.
I hope this description makes sense. Anyone use them and am I missing something in trying to work out exactly what they are for?