USE Blender python As a Step tool and code it all in python like a real programmer

blender_cad.py

import bpy
from mathutils import Euler, Vector
import math
import bmesh

def set_origin_to_bottom_center(obj):
    """
    Sets the origin of the given object to its bottom center.

    Args:
        obj (bpy.types.Object): The object whose origin will be set.
    """
    # Ensure the object is active and selected
    bpy.ops.object.select_all(action='DESELECT')
    obj.select_set(True)
    bpy.context.view_layer.objects.active = obj

    # Calculate the bounding box in local coordinates
    bbox_corners = obj.bound_box
    min_z = min([corner[2] for corner in bbox_corners])
    max_z = max([corner[2] for corner in bbox_corners])

    # Calculate the bottom center in local coordinates
    center_x = (max([corner[0] for corner in bbox_corners]) + min([corner[0] for corner in bbox_corners])) / 2
    center_y = (max([corner[1] for corner in bbox_corners]) + min([corner[1] for corner in bbox_corners])) / 2
    bottom_center_local = (center_x, center_y, min_z)

    # Transform the local bottom center to world coordinates
    bottom_center_world = obj.matrix_world @ Vector(bottom_center_local)

    # Set the 3D cursor to the bottom center
    bpy.context.scene.cursor.location = bottom_center_world

    # Set the origin to the 3D cursor
    bpy.ops.object.origin_set(type='ORIGIN_CURSOR')


import bpy
from mathutils import Vector

def create_cube(location, dimensions, name):
    """
    Creates a cube by stitching vertices together at the specified location and dimensions,
    and sets its origin to the bottom center.

    Args:
        location (tuple): A tuple (x, y, z) specifying the bottom center of the cube.
        dimensions (tuple): A tuple (x, y, z) specifying the cube's dimensions.
        name (str): The name to assign to the cube.

    Returns:
        bpy.types.Object: The created cube object.
    """
    # Calculate half dimensions
    hx, hy, hz = dimensions[0] / 2, dimensions[1] / 2, dimensions[2]

    # Define the vertices of the cube
    vertices = [
        
        Vector((-hx, -hy, 0)),  # Bottom face
        Vector((hx, -hy, 0)),
        Vector((hx, hy, 0)),
        Vector((-hx, hy, 0)),
        Vector((-hx, -hy, hz)),  # Top face
        Vector((hx, -hy, hz)),
        Vector((hx, hy, hz)),
        Vector((-hx, hy, hz)),
    ]

    # Define the faces using the vertices
    faces = [
        (0, 1, 2, 3),  # Bottom face
        (4, 5, 6, 7),  # Top face
        (0, 1, 5, 4),  # Side faces
        (1, 2, 6, 5),
        (2, 3, 7, 6),
        (3, 0, 4, 7),
    ]

    # Create a new mesh and object
    mesh = bpy.data.meshes.new(name)
    cube_object = bpy.data.objects.new(name, mesh)

    # Link the object to the scene
    bpy.context.collection.objects.link(cube_object)

    # Create the mesh from vertices and faces
    mesh.from_pydata(vertices, [], faces)
    mesh.update()

    # Move the object to the correct location
    cube_object.location = Vector(location)

    # Set origin to bottom center
    bpy.context.view_layer.objects.active = cube_object
    bpy.ops.object.origin_set(type='ORIGIN_CENTER_OF_MASS', center='BOUNDS')

    return cube_object


def create_cylinder(location, r, height, name, rotation=(0, 0, 0)):
    """
    Creates a cylinder at the specified location with the given radius and height
    and sets its origin to the bottom center.

    Args:
        location (tuple): A tuple (x, y, z) specifying the cylinder's location.
        r (float): The radius of the cylinder.
        height (float): The height of the cylinder.
        name (str): The name to assign to the cylinder.
        rotation (tuple): A tuple (x, y, z) specifying the rotation in radians.
    
    Returns:
        bpy.types.Object: The created cylinder object.
    """
    bpy.ops.mesh.primitive_cylinder_add(location=location, radius=r, depth=height)
    cylinder = bpy.context.active_object
    cylinder.name = name
    cylinder.rotation_euler = Euler(rotation)

    # Set origin to bottom center
    set_origin_to_bottom_center(cylinder)

    return cylinder


def clear_scene():
    """Deletes all objects in the current scene."""
    bpy.ops.object.mode_set(mode='OBJECT')
    bpy.ops.object.select_all(action="SELECT")
    bpy.ops.object.delete(use_global=False)



def subtract_model(obj1, obj2, remove=True, fast_mode=True):
    """
    Subtracts obj2 from obj1 using a Boolean modifier.
    Optionally removes obj2 from the scene after the operation.
    Allows switching between Fast and Exact modes.
    """
    if obj1 is None or obj2 is None:
        print("Error: One of the objects is None. Cannot perform Boolean operation.")
        return
    if boolean_disable:
        print("Boolean operations are disabled. Skipping subtraction.")
        return

    # Add a Boolean modifier to obj1
    bool_mod = obj1.modifiers.new(name="BooleanModifier", type="BOOLEAN")
    bool_mod.object = obj2
    bool_mod.operation = "DIFFERENCE"

    # Set the solver to Fast or Exact
    bool_mod.solver = "FAST" if fast_mode else "EXACT"

    # Apply the modifier
    bpy.context.view_layer.objects.active = obj1
    bpy.ops.object.modifier_apply(modifier=bool_mod.name)

    # Optionally remove obj2
    if remove:
        bpy.data.objects.remove(obj2)


def add_model(obj1, obj2, remove=True, fast_mode=True):
    """
    Adds obj2 to obj1 using a Boolean modifier.
    Optionally removes obj2 from the scene after the operation.
    Allows switching between Fast and Exact modes.
    """
    if obj1 is None or obj2 is None:
        print("Error: One of the objects is None. Cannot perform Boolean operation.")
        return
    if boolean_disable:
        print("Boolean operations are disabled. Skipping addition.")
        return

    # Add a Boolean modifier to obj1
    bool_mod = obj1.modifiers.new(name="BooleanModifier", type="BOOLEAN")
    bool_mod.object = obj2
    bool_mod.operation = "UNION"

    # Set the solver to Fast or Exact
    bool_mod.solver = "FAST" if fast_mode else "EXACT"

    # Apply the modifier
    bpy.context.view_layer.objects.active = obj1
    bpy.ops.object.modifier_apply(modifier=bool_mod.name)

    # Optionally remove obj2
    if remove:
        bpy.data.objects.remove(obj2)


def duplicate_model(obj, new_name):
    """
    Duplicates an object and assigns it a new name.

    Args:
        obj (bpy.types.Object): The object to duplicate.
        new_name (str): The name to assign to the duplicate object.
    
    Returns:
        bpy.types.Object: The duplicated object.
    """
    if not obj:
        print("Error: No object provided to duplicate.")
        return None
    
    # Deselect all objects
    bpy.ops.object.select_all(action='DESELECT')

    # Select the object to duplicate
    obj.select_set(True)
    bpy.context.view_layer.objects.active = obj

    # Duplicate the object
    bpy.ops.object.duplicate()
    duplicate = bpy.context.active_object
    duplicate.name = new_name

    # Set origin to bottom center for the duplicate
    set_origin_to_bottom_center(duplicate)

    return duplicate

def remove_object(obj2):
    bpy.data.objects.remove(obj2)
# Global flag to disable Boolean operations
boolean_disable = False


# Clear the scene
clear_scene()


def make_iron_holder():
    # Create the main cube with correct dimensions and origin
    main_obj = create_cube(location=(0, 0, 0), dimensions=(20, 20, 20), name="Part")

    # Create the cylinder and add it to the main cube
    cylinder = create_cylinder(location=(10, 0, 0), r=10, height=20, name="Cylinder_rounding")
    subtract_model(cylinder,main_obj,False)
    add_model(main_obj, cylinder)

    #drill out 17 dia
    cylinder = create_cylinder(location=(10, 0, 10), r=17/2, height=13, name="Cylinder17mm")
    subtract_model(main_obj,cylinder)

    #center 14 dia
    cylinder = create_cylinder(location=(10, 0, -3), r=14/2, height=20, name="Cylinder14mm")
    subtract_model(main_obj,cylinder)

    #ceneter 14 dia
    cylinder = create_cylinder(location=(15, 0, -3), r=13/2, height=35, name="Cylinder13mm_bore")
    subtract_model(main_obj,cylinder)




    obj_sdh =  create_cube(location=(0, 25, 0), dimensions=(20, 30, 20), name="side_cord_holder")

    # Create the cylinder and add it to the main cube
    cylinder = create_cylinder(location=(00, 40, 0), r=10, height=20, name="sh_rounding")
    subtract_model(cylinder,main_obj,False)
    add_model(obj_sdh, cylinder)

    # drill out 12
    cylinder = create_cylinder(location=(0, 40, 0), r=12/2, height=20, name="sh_Cylinder12mm")
    subtract_model(obj_sdh,cylinder)

    # drill out 17
    cylinder = create_cylinder(location=(0, 40, 7), r=17/2, height=20, name="sh_Cylinder17mm")
    subtract_model(obj_sdh,cylinder)

    #ceneter 14 dia
    cylinder = create_cylinder(location=(0, 50, 7), r=13/2, height=35, name="sh_Cylinder13mm_bore")
    subtract_model(obj_sdh,cylinder)

    add_model(main_obj,obj_sdh)
    








def merge_nerby_vertices(obj, threshold=0.001):
    """
    Merges nearby vertices in the given object based on the threshold distance.

    Args:
        obj (bpy.types.Object): The object whose vertices will be merged.
        threshold (float): The maximum distance between vertices to merge.
    """
    bpy.context.view_layer.objects.active = obj
    bpy.ops.object.mode_set(mode='EDIT')
    bpy.ops.mesh.select_all(action='SELECT')
    bpy.ops.mesh.remove_doubles(threshold=threshold)
    bpy.ops.object.mode_set(mode='OBJECT')
        


def make_caliper_holder():

    # cut slot out
    def cut_slot(main_obj):
        cutter = create_cube(location=(1,0,1.6),dimensions=(26,16.3,10.6),name="cutter_slot")
        subtract_model(main_obj,cutter)
        
        
    def cut_bottom_slant(main_obj):
        cutter = create_cube(location=(7.6814,0,0.5521),dimensions=(6,15.8,6),name="cutter_bottom_slot")
        rotation=(0,0.244346,0) # ~14 degree
        cutter.rotation_euler = Euler(rotation)
        subtract_model(main_obj,cutter)



    def make_lid(main_obj):
        lid = create_cube(location=(0, 0, 8.7), dimensions=(19, 27.4, 1.4), name="Lid")
        subtract_model(lid,main_obj,remove=False)# make a negative impression on the lid of the box to make it fit
        
        rotation=(0,3.14,0) # flip the lid face down
        lid.rotation_euler = Euler(rotation)
        lid.location.x= 25
        lid.location.y=0
        lid.location.z = 0
        
        
    main_obj = create_cube(location=(0, 0, 0), dimensions=(20, 28, 9.5), name="Part")
    cut_slot(main_obj)
    cut_bottom_slant(main_obj)
    merge_nerby_vertices(main_obj,0.05) # merge vertices within 0.05 distance

    lid = make_lid(main_obj)
    
    
make_caliper_holder()

this is example output

I made it look cooler