This preset is built from a simple box ! The chamfered edges effect is done within the shader and You can easily adjust it in the VrayEdgesTex that is in the bump slot of the material (adjust the rounded corners radius value). You can easily adjust the following parameters of the railing: height, picket spacing, handrail depth, handrail height, handrail shift, picket width, picket depth and bottom rail On/Off

You can easily adjust the following parameters of the railing:
--- height
--- picket spacing
--- handrail depth
--- handrail height
--- handrail shift
--- picket width
--- picket depth
--- bottom rail On/Off

UPDATE (22.06.2020):
Added a bottom rail as an option, You can turn it On/Off