BevelShapeCreator.py

import bpy

def createProfile(width, height, roundness, curveName="bevel", collectionName="bevelCollection"):
    curveData = bpy.data.curves.new(curveName, type='CURVE')
    curveData.dimensions = '2D'
    curveData.resolution_u = 8

    radius = height/2 * roundness
    handleDistance = 4/3 * radius

    xCoord = width/2 - radius
    yCoord = height
    
    point1 = [(-1*xCoord, 0, 0), (-1*(xCoord + handleDistance),0,0), (-1*(xCoord - handleDistance),0,0)]
    point2 = [(xCoord, 0, 0), (xCoord - handleDistance,0,0), (xCoord + handleDistance,0,0)]
    point3 = [(xCoord, -1*yCoord, 0), (xCoord + handleDistance, -1*yCoord, 0), (xCoord - handleDistance, -1*yCoord, 0)]
    point4 = [(-1*xCoord, -1*yCoord, 0), (-1*(xCoord - handleDistance), -1*yCoord, 0), (-1*(xCoord + handleDistance), -1*yCoord, 0)]

    coords = [point1, point2, point3, point4]

    polyline = curveData.splines.new('BEZIER')
    polyline.bezier_points.add(len(coords)-1)
    polyline.use_endpoint_u= True;
    polyline.use_cyclic_u = True;


    for i, coord in enumerate(coords):
        polyline.bezier_points[i].co = coord[0]
        polyline.bezier_points[i].handle_left_type = 'FREE'
        polyline.bezier_points[i].handle_left = coord[1]
        polyline.bezier_points[i].handle_right_type = 'FREE'
        polyline.bezier_points[i].handle_right = coord[2]

    # create Object
    curveOB = bpy.data.objects.new(curveName, curveData)
    curveOB.data['width'] = width
    curveOB.data['height'] = height

    collection = ""
    if (collectionName in bpy.data.collections.keys()):
        collection =  bpy.data.collections.get(collectionName)
        
    else:
        collection =  bpy.data.collections.new(collectionName)
        bpy.context.scene.collection.children.link(collection)
        collection.hide_viewport = True

    collection.objects.link(curveOB)



if __name__ == "__main__": createProfile(0.5,0.2,1)