I believe the popular route is Fusion. (Decidedly NOT open source)
Here's an example: say you want to punch some holes to mount components on a chassis. Say, furthermore, that you want to mount those components at an angle.
Here's what you do in Fusion:
1. Draw a sketch.
2. Rotate the component on the sketch about its center.
3. Subtractively extrude holes through the chassis.
In Fusion this is trivial and natural. Believe it or not, FreeCAD does not support #2. Want to mount several components at different angles? Fuck you, you need to draw each one of them pre-slanted already.
Select the object, set orientation in Placement / Axis / x,y,z
- Create a square via the CreateSquare[0] icon
- Put the lines as construction line
- Constrain the holes to the corners of the square.
- Add an angle constraint on one side of the square as you need.
It's easier than constraining your holes on a rectangle on which you have to replace the horizontal and vertical constrains afterwards. And you get to keep all those parametric variables that make changing something afterwards so easy.
In your case one can for example use use the NormalToEdge map mode, specify the degrees of Roll, and then use a Pocket operation on the sketch to make the holes at that angle.