I'm experimenting with using a Moire interference pattern to make a model's mouth look like it is moving.

I've constructed a core – shown above, around which I've run a paper belt with angled stripes. The core is my usual brand of thin card whilst the belt is made of paper to keep it flexible.

The belt fits around the core slightly loosely and is free to move.

I fixed the back of the paper belt to the back of the body, now as the legs are pulled up and down relative to the body the belt will roll round the core.

I then wrapped the body round the core and glued it closed.

I've added eyes and arms to finish off the model. Now as the body moves up and down the mouth makes an interesting interference pattern! I'm going to try out a couple of different angles with the mouth and the stripes but should have a prototype for you to play with soon.