Nothing too complicated with this tool. Just some scrap 1/8 stainless rod stock, with some scrap maple (or whatever wood you have on hand) and you can make this handy little tool.

For me personally I use a scribe often since I have a bad habit of overhandling the wood while I'm doing my layout and I hate smudging my pencil lines. Plus it really helps to establish a knife wall for sawing etc...

There's no "right" way to make a scribe, just use what you have and I'm sure you'll be fine. This one I'll relegate to using on darker woods where pencil lines might not show up and I might not have chalk on hand.

Anyways, enjoy!