Same as IamSly's version, except made the lip optional and made it available to the Customizer.
If you need an even more custom version, or you need one printed, let me know.
IamSly recommends printing vertically with concentric supports (available in Cura, but not Slic3r). This will minimize the amount of support material and simplify support removal. I would print it horizontally with supports if you need it as strong as possible. Internal supports might be a bugger to remove, though.