Well, going so 2

While I'm working mostly only undemanding things made of wood where it does not depend on half a millimeter, but the holes in the angles are so large that I could put three mechanical pencils alongside each other in a hole.

If one takes NEN thick blunt pencil, one can use the holes to some extent.
This is of course far from exact.

The metal is not really plan for the rest. It's a little bit curved, so you have the length 1 to 2 millimeter difference, yes on whether you press down the angle or just hangs up.

The scale printed differs also 30cm approximately 1 to 2 millimeters of all my other instruments from ('m not a calibrated, so I can not say what is the exact scale, but the thing I no longer confidential ;-)

I would not buy it again.