I am looking for a source to buy a holder of a drag engraving tool or a pen refill, like the simple spring loaded design that appeared in the Fall 2007 of Digital Machinist. Since I don't have a lathe (wish!) I was looking for a cheap source of something like this - something with a 1/4 inch stem that can be colleted into a trim router, and something with an 1/8 inch hole at the other that a drag engraving tool or a pen refill can be set screwed in place. By changing springs you set the force applied on the surface.
Anyone have one and if so, where did they get it?

TIA,