Personally, I do not like the type of marker, such as this one, which does not enable both the line at the top and the angled line to be scribed at the same time, which minimises marking errors. This marker only scribed the diagonal.
Good markers:
Shopmade for angle brass ...
Ditto from perspex ...
And a great one from LN (no longer available, but this was designed by Rob Cosman, who sell wooden versions) ...
A sliding bevel can be used, but is limited in its range as it only does the angle ...