The physical construction of the arms was done by @paulobarcelos I believe, Maybe he has a template somewhere? What makes them curl up is the motor pulling fishing line connected to the top of the arms. The 5 fishing lines are connected to the motor with a 5legged strawbee that in turn have 5 one legged strabees as ancors for the lines. (i think.. you might have to experiment with how the lines are pulling, to get the movement right.
in this particular gif the movement is trigged by a sound input backpack, this is a hack that requires some extra electronics, currently not available from us, but you could trigger the movement by touch or light input instead!
This is how to to it with touch:
Play with the min and max values in Circuit Touch to get the right amount of movement.