If you create a user section without any radius at the corners, like the one below, you cannot unfold it afterwards and the option "Unwind profile" is grayed.
In order to unfold a user section, correct radius values have to be defined at the corners, like sample below:
When you now create a beam with this section shape ("User section 2" in our case), the option "Unwind profile" is available and can be selected in the "Beam" properties dialog.
To unfold a user section on workshop drawings, you just need to use a specific drawing style, like the one mentioned in the print-screen below:
The created drawing could look like the following example.