Farily bold for me to do a blender tutorial, but heck, maybe it’s useful for someone ;). Blender has a way to bevel a shape along a path. Now it also includes a way to define a mask how this shape is scaled along the path. This is done with another path object. It’s called a Taper Object (in F9 edit buttons). Make sure you define the shape relative to Y=0 in edit mode. You can have move it to negative numbers, but it may give weird results.