I stripped back the model that I'd created yesterday and I've scanned and made appropriate adjustments to the parts layouts. The scissor arm unit is fastened top and bottom inside the body. In the stage that I was at yesterday the tabs holding the scissors were glued into the centre of a flat surface. The problem with this is that the surface flexes as the tab is pulled. To get over this problem I have added a crease into the centre of each surface.
It only needs a single crease to dramatically increase the stiffness of a structure.
I completed assembling the parts and it all works quite nicely! I'll be doing another draft before starting with colour and artwork, The relative size and positioning of the parts needs some serious work!
It's coming on though.