I've completed the double crank mechanism and done the photography ready for the instructions. If you are waiting for the parts to have a try yourself I'm afraid you are going to have to wait another day. Apparently there is some sort of family celebration coming up and I've called upon to assist in the preparations. I know! Don't they realise that there is cardboard engineering to be done?!
Anyway, to keep you going, I've put together this animation so you can see what I've been talking about. I really like the fluidity and organicness (is that a word?) of the movement. Hope you like it too!