Make a stencil of some shape, then take some sandpaper to it.
Fairly painful, but supposing you don't do it too deep it will only be temporary.
*may not be good advice*
(
Jeru War and Piss,
Thu 17 Apr 2008, 0:54,
archived)
Do it then.
You could probably make a stencil out of one of your black and white painting things.
(
Jeru War and Piss,
Thu 17 Apr 2008, 1:06,
archived)