C Craft,
Yes! Whatever doesn't have tape on it will etch. And scotch tape, the shiny kind (probably any plastic tape would work), is a resist so the etcher won't remove anything covered by it. After a while the heat of etching builds up and the glue begins to let go. I'd practice on a piece of scrap.
I went to the local craft store hoping I could find some pre-cut round tape "thingies" that I could stick over the pivot hole for a more finished look, because cutting a circle is difficult, but couldn't find any.
The reason I did this was because I used 304 SS for the liners. It is cheap but not "free machining" meaning that it was difficult to mill the relief. I'm lucky to have a friend with a mill, also a fellow knife maker", and we ripped up a set of liners trying to mill them. So, after looking at how deep an etch you can make with a stencil I thought this might work. But, I does take a while.