Another possiblity for your lettering would be using electoluminescent wire. It's cheap and easy to manipulate, end result looks like neon in whatever colour you choose.
However, the smallest diameter I can find is 1.2mm, and it does need a driver/inverter to fire it, but not expensive.
One example in this instructible: http://www.instructables.com/id/How-to-make-EL-Wire-Art/
Peter