Mechanical Blowfish

This is a (i hope) working model of blowfish. To assemble you need a M4 screw and nut, the screw hex head shoud be placed in the nail and the nut in the lower part of the head. The external and the internal body should be placed like the picture, when you rotate the nail every flexible part of the body will assume an arc shape to rapresent the defensive status of the fish :D. The internal body should cover the gap between the externals when compressed, hiding the screw.
I've not tired yet beca