Google the phone number 800-435-2931
www.gcwaldom.com
Didn't find pens though.
didn't Staedler have suppliers around the world ?
seems an office supply place might offer some options.
or, paint the whole board and with a small rotary cutter/scratcher,
scratch off what you don't want, and leave the trace.
Dave
> It says
> > 1-800-435-2931 customer service. A division of GC thorsen Inc.