This post covers the making of the mechanism to open and close this piece and follows some of the different versions it went through to reach the end result ( assuming this does turn out to be the way it ends up )
Working out the position of the main arm using a piece of card.
Another piece of card is used to work out the link between the main arm and the top half.
The link and arm are made and assembled in this photo, but I was not happy with the handle on the arm.
This shot shows the catch mechanism, the handle has also been changed,but it was still not quite right.
This is how it finished up, and I think I might leave it at that, for now at least.