from tkinter import *
class Packing:	
    def __init__(self,instancia):

        self.container1=Frame(instancia)
        self.container2=Frame(instancia)
        self.container3=Frame(instancia)
        
        self.container1.pack()
        self.container2.pack()
        self.container3.pack()

        Button(self.container1,text='B1').pack()
        Button(self.container2,text='B2').pack(side=LEFT)
        Button(self.container2,text='B3').pack(side=LEFT)

        self.b4=Button(self.container3,text='B4')
        self.b5=Button(self.container3,text='B5')
        self.b6=Button(self.container3,text='B6')
        
        self.b6.pack(side=RIGHT)
        self.b4.pack(side=RIGHT)
        self.b5.pack(side=RIGHT)        
        

raiz = Tk()
Packing(raiz)
raiz.mainloop()
		
		
