I use the foam cylinders from my local shop. They come in different colors and sizes, I use the 3/8 and 1/2 inch sizes. I have a bit that goes in my dremel tool to turn them down with.
As far as the paint goes, sometimes I will use the foam color as the base color, and if I want a different color, I either spray paint the body, or use acrylic paint from the craft store as a base. After the base color is on, I use a small piece of fine mesh stretched over the body and held tight with an old pair of forceps to make the scales. I use cheap flat black spray paint to spray a light coat on and remove the mesh after it dries a little. Then it is just a matter of giving it a few light coats of Liquid Fusion. It is very easy to do the paint. Have fun and let me know if you need any help, I will be glad to help you out!