Pencil lead is graphite, and hard is like #4 or bigger number. A regular pencil is #2. Art stores have such pencils, maybe even with "lead" up to 1/8". Best is to find an old vcr motor or such and salvage the brushes. Another souce I have used are old fashion batteries that have a carbon (graphite) rod in them, a AAA would be a little bigger than 1/8 but it's easy to sand down in a drill. Just watch the gray goop in them batteries as it's poison and mildly caustic. When I was a kid we use to cut D cells open with a saw all the time to make carbon arc lights. Sharpen the rods in a pencil sharpener, put them in spring clothes pin with a piece of zip cord, plug them in, and touch them lightly together. Made one bright light it did. You could feel the heat come off them. Man, were we nuts or what? FRED