This is a Parametric Shelf Bracket that can be used in either a classic underneath the shelf style or as an over the shelf hanging down style bracket (see pics). The parameters that can be accessed in Fusion 360 are:
Board Thickness: How thick is the board you plan to put in the slot for use in the 'over' style. A lumber yard 1x6 will measure approximately 18.5mm by 140mm due to sanding and facing losses. Enter 19mm in this case for a snug fit around a 1x6.
Board Width: As above a 1x6 will measure approximately 140mm wide. A 1x8 would be 191mm etc. The supplied model fits a standard 1x6 at 140mm.
Bracket Thickness: How thick do you want the perimeters of the bracket to be? I've chosen 5mm which works well. This measurement drives some other measurements so tinker at your own risk.
Bracket Height: The length of the "other side" of the bracket when used as an overhanging bracket. Ideally this should be as close to the width of the board as possible given the available height of the bracket. 120mm for a 1x6 is a nice compromise for using in both directions.
Please enjoy!