Best one I ever used was made from an old hacksaw blade.
I ground the remaining teeth off of the blade and used a cutoff wheel to open a slot on an angle to where one of the holes were in one end. Bade a piece of broom handle into a handle buy cutting a slot and wedging the other end in and drilling for a screw to go into that hole.
This allows you to get into very narrow places, but it also will not "Kick back" it it comes in contact with the wrong part of a spinning chuck.
If this happens the blade just turns into a Z and you can straighten it back out, but no one would ever do this under power anyway.
Right?