Most insulated wire is too large. I use bare copper wire, and then paint it. Electronics supply houses no longer carry a good stock of fine wire (so-called magnet wire). Michaels craft stores feature some pretty fine wire in their beading and jewelry area. I also rip transformers off of electronics I junk, and take them apart to get the fine wire inside. Most of it is coated with a varnish, and it paints well.