Create the absolute level with the Base point in the midpoint of the section.

(Here in figure bottom "Fixed plane 1")

Fixed plane 1 - Base point

In the context menu, click on Insert new plane....

In the Type list field, select the point Plane with distance.

In thed Distance field, enter the following:

IF SAY = 0 THEN SDX ELSE SDY ENDIF

In the following example, the miter angle is 45°.

The resulting Distance both are 40 mm.

Base miter start

Again click on the Insert new plane... context menu.

In the Type list field, select the point Plane with rotation.

In the Angle field, enter "SAY".

In the Turn around list field, select point X axis.

In our example, "SAY" has 45°.

=> The plane is moved 45° around the X-axis.

Rotation miter start Y

Create a Plane with rotation again.

Under Angle enter the following:

IF SAY = 0 THEN SAX ELSE 0 ENDIF

(Only SAY or SAX are recognized)

In the list field Turn around, select point Y axis.

In our example, the rotation occurs around the Y-axis 0°.

Create a sketch for the Extrusion solid and enter the following:

Length:

IF SDY = 0 THEN SDX*2 ELSE SDY*2 ENDIF

Set a checkmark at Only create, if.

The Cut extrusion should only be created if SAY or SAX are unequal to '0'.

Cut extrude 1

Then create the sketch with the connection points.

Sketch with connection points