I remember seeing a website a year or so ago where a guy made a replica of a racing badge for his classic car... Basically, he sculpted it, molded it, cast it in metal, then colored it in with some sort of paint pen. The object colored with the paint pen could then be baked in an ordinary oven to harden the paint, like enameling but at a lower temperature. Does anyone know what these paint pens are called? I swear the name is on the tip of my tongue!
edit: Found! Thanks to Clio_75
http://www.artmaterials.com.au/index.php?cPath=235_161