setup_environment_mm.py

import bpy
from addon_utils import check, enable
C = bpy.context
D = bpy.data

SCALE_LENGTH = 0.001
LENGTH_UNIT = 'MILLIMETERS'
MASS_UNIT = 'GRAMS'
CLIP_END = 100000
PRINT_UTIL = "object_print3d_utils"

def config_units():
    C.scene.unit_settings.scale_length = SCALE_LENGTH
    C.scene.unit_settings.length_unit = LENGTH_UNIT
    C.scene.unit_settings.mass_unit = MASS_UNIT

def config_viewports():
    screens = D.screens
    viewareas = [area for screen in screens for area in screen.areas if area.type == 'VIEW_3D']
    for area in viewareas:
        area.spaces.active.overlay.grid_scale = SCALE_LENGTH
        area.spaces.active.clip_end = CLIP_END

def enable_print_util():
    is_enabled, is_loaded = check(PRINT_UTIL)
    if is_enabled and is_loaded:
        return
    bpy.ops.preferences.addon_enable(module=PRINT_UTIL)

def remove_default_objects():
    bpy.ops.object.select_all(action='SELECT')
    if len(C.selected_objects) <= 3:
        bpy.ops.object.delete(use_global=True)

config_units()
config_viewports()
enable_print_util()
remove_default_objects()