Box reference (Form)
In the Form contextual environment, the Box command creates a T-Spline body in the shape of a primitive box in Fusion.
Design > Form > Create > Box 
Length
Specifies the distance in the length direction.
Length Faces
Specifies the number of faces in the length direction.
Width
Specifies the distance in the width direction.
Width Faces
Specifies the number of faces in the width direction.
Height
Specifies the distance in the height direction.
Height Faces
Specifies the number of faces in the height direction.
Height Direction
Specifies whether the height values is in one direction or both directions.
Symmetry
Enables mirror symmetry on the box.
- Length Symmetry Enables symmetry on the length of the box.
- Width Symmetry Enables symmetry on the width of the box.
- Height Symmetry Enables symmetry on the height of the box.
New Component
Specifies the effect the operation has on the design.
- New Body The operation creates a new body.
- New Component The operation creates a child component in the active component.