簡単なPySideプログラム

# -*- coding: utf-8 -*-

import maya.cmds as cmds
import maya.mel as mel

from PySide.QtCore import * 
from PySide.QtGui import * 
from shiboken import wrapInstance 
from maya import OpenMayaUI as omui 
from maya.app.general.mayaMixin import MayaQWidgetBaseMixin
from pprint import pprint

import maya.OpenMaya as OpenMaya
import maya.OpenMayaMPx as OpenMayaMPx

mayaMainWindowPtr = omui.MQtUtil.mainWindow()
mayaMainWindow = wrapInstance(long(mayaMainWindowPtr), QWidget) 

class CreatePolygonUI(QWidget):    
    def __init__(self, *args, **kwargs):        
        super(CreatePolygonUI, self).__init__(*args, **kwargs)
        
        #Parent widget under Maya main window        
        self.setParent(mayaMainWindow)        
        self.setWindowFlags(Qt.Window)   
        
        #Set the object name     
        self.setObjectName('CreatePolygonUI_uniqueId')        
        self.setWindowTitle('Create polygon')        
        self.setGeometry(50, 50, 250, 150)        
        self.initUI()        
        self.cmd = 'polyCone'

    def initUI(self):        
        #Create combo box (drop-down menu) and add menu items 
        self.combo = QComboBox(self)        
        self.combo.addItem( 'Cone' )        
        self.combo.addItem( 'Cube' )        
        self.combo.addItem( 'Sphere' )        
        self.combo.addItem( 'Torus' )        
        self.combo.setCurrentIndex(0)        
        self.combo.move(20, 20)        
        self.combo.activated[str].connect(self.combo_onActivated)        

        #Create 'Create' button
        self.button = QPushButton('Create', self)        
        self.button.move(20, 50)        
        self.button.clicked.connect(self.button_onClicked)                    

    #Change commmand string when combo box changes
    def combo_onActivated(self, text):        
        self.cmd = 'poly' + text + '()'            

    #Execute MEL command when button is clicked
    def button_onClicked(self):        
        mel.eval( self.cmd )    

class HelloWorld(OpenMayaMPx.MPxCommand):
    def __init__(self):
        OpenMayaMPx.MPxCommand.__init__(self)
 
    def doIt(self, argList):
        ui = CreatePolygonUI()
        ui.show()
        return
 
def creator():
    return OpenMayaMPx.asMPxPtr( HelloWorld() )
 
def initializePlugin(obj):
    plugin = OpenMayaMPx.MFnPlugin(obj, 'plugin', '1.0', 'Any')
    try:
        plugin.registerCommand('helloWorld', creator)
    except:
        raise RuntimeError
 
def uninitializePlugin(obj):
    plugin = OpenMayaMPx.MFnPlugin(obj)
    try:
        plugin.deregisterCommand('helloWorld')
    except:
        raise RuntimeError

プラグインとしてロードして、MELスクリプトからhelloWorldで呼び出すと、ダイアログが表示されプリミティブを作れます。

参考

https://knowledge.autodesk.com/ja/search-result/caas/CloudHelp/cloudhelp/2016/JPN/Maya-SDK/files/GUID-3F96AF53-A47E-4351-A86A-396E7BFD6665-htm.html