Firefly Plush Toy

I am going to make a Firefly Plush toy with a light up bum. I want to use soft materials that so that it feels like a pillow and wings with a mesh like material. The details will be embroider stitched to give it a handmade feel. I will only need a few LEDs and a simple switch so might opt to use a coin cell battery holder. I am not sure if I want to incoporate Arduino but it would be nice to have the LEDs flickr. If I use Arduino I am considering trying RGB LEDs to play with color. Miss Becky, what do you think?