Following from the butterfly model I was wondering if it would be possible to make a dragonfly with two pairs of wings that moved in opposite directions just like the real thing. That is, front pair of wings goes up, back pair of wings go down then front pair go down, back pair go up.

I tend to do a lot of my planning in my head, just thinking mechanisms through while I'm walking or driving or having a conversation, basically whenever I'm doing other stuff I should really be concentrating on. Anyway, after lots of over-elaborate ideas I settled on this as a plan.

Two pendulums facing each other joined by a simple linkage. I only put coins on one pendulum, figuring that if I put them on both it would but a strain on the linkage. 

You can just make out the coins to the left of the linkage above. 

The result, the pendulum swings when the box is moved. As it does so, one side goes up and the other side goes down.

Now to figure out how the pendulums will link to the wings. Notice, if you will, that the dragonfly in the  picture is rotated 90 degrees compared to the way the butterfly was constructed.

Don't worry, I haven't forgotten the swinging legs model, just needed to test this out.